United States
>nm«ntal Protection
Agency
Office of
Pesticide Programs
Integrated Pest Management Unit
December 1979
Washington DC 20460
:ides
Common Sense
Pest Control for
the Home and Garden
December 1979
-------
COMMON SENSE PEST CONTROL
FOR THE HOME AND GARDEN
Helga Olkowski
\\
William Olkowski
Produced under contract for the Environmental
Protection Agency, Local Region IX by:
Center for the Integration of the Applied Sciences
a division of the John Muir Institute
-------
This pamphlet has been prepared by the Center for the Integration of
Applied Sciences (CIAS), a division of the John Muir Institute for Environmental
Studies, Inc., under contract with the U.S. Environmental Protection Agency (EPA),
Region IX.
CIAS has worked for several years under the direction of William and Helga
Olkowski to develop effective integrated shade tree pest management programs for
a number of California cities. Current CIAS work also includes an IPM for flood
control levees for the California Department of Water Resources; development of
urban IPM implementation plans for the California Department of Food and Agricul-
ture; several parasite importation and distribution projects; the development of
an IPM program for the National Capitol Region of the National Park Service
(Washington, D.C.); and an EPA contract to establish a computerized data base
for urban insect pests (including their predators, parasites, habitat, etc.) in
the continental United States. In addition, through a cooperative agreement with
EPA, CIAS is developing a pilot technical assistance center in urban IPM and
alternatives to pesticide use for communities across the nation. A list of the
Center's publications may be obtained by writing to CIAS, 1307 Acton St., Berkeley,
CA 94706, or phoning (415) 524-8404.
The John Muir Institute for Environmental Studies, Inc., is a non-profit
scientific research and educational organization which seeks scientific information
to expand knowledge about natural systems and the role of people in those systems.
It seeks new policy approaches to improve the ways in which society manages, uses,
and protects natural resources. Natural scientists, social scientists, and legal
specialists are brought together to explore a range of technical and policy problems,
Particular emphasis is given to air quality and visibility, energy development,
water resources, forestry practices, chemicals in the environment, and urban
ecosystem management.
The Institute specializes in research problems which have not been widely
or effectively recognized—for example, visibility as an important national
resource, especially in the West; urban pesticide use; long-range cumulative
impacts of forestry practices; or the interrelationships between groundwater and
surface water in areas subject to intensive energy development. The Institute
is interested as much in the social, economic, and institutional aspects of
environmental problems as it is in the technical and physical aspects. Relevance
to policy issues is a major criterion for the selection of research problems.
Common Sense Pest Control was prepared with the assistance of:
Diane Kuhn, Lisa Haderlie, drawings
Frederica Bowcutt, Gina Rosenberg, layout and design
Produced under contract (58-10-4475)
for the Environmental Protection Agency
Contract Management
Region IX
Robert G. Kuykendall
Jerelean Johnson
copyright - John Muir Institute - December, 1979
The cover droving is of the common ground beetle_ in -the San Francisco Bay area,
Pteros-ickus sp., which feeds on caterpillars, worms, and a variety of soil organisms.
-------
COMMON SENSE PEST CONTROL FOR THE HOME AND GARDEN
Table of Contents:
List of Figures 3
I. What Controls Insects "Naturally"? 4
Climate 4
Habitat and Food 4
Disease. . 7
Parasites and Predators 7
II. If Natural Controls Are So Great, Why Don't They Work? 14
Exclusion of Natural Enemies - .... 14
Seasonal Fluctuations 14
Invaded Insects 14
Susceptible Plants 17
Plants Under Stress 17
III. What's a Safe Pesticide I Can Use? 19
Problems Associated with Pesticide Use:
Residue - The Meaning of LD5Q 19
Resurgence 20
Secondary Pests 22
IV. What Should I Do? 23
The Theory: Integrated Pest Management 23
Some Specific Examples: 23
Snails 23
Aphids, Mealybugs, Scales, Whiteflies 24
Bees, Wasps 27
Caterpillars - How to Use B.. t_ 27
Cabbage Maggots, Garbage Flies 30
Cockroaches, Ants, Food Moths, Fleas, Rats 30
Dutch Elm Disease - The Difference Between Elm Bark Beetles
and Leaf Feeding Beetles 33
V. Summary of Control Methods 35
VI. How Can I Get More Information? 36
VII. Scientific Names of Common Insects and Insect Families Mentioned
in the Text 37
-2-
-------
List of Figures
pages
Figure 1. Common housefly 5
Figure 2. Tomato hormworm 5
Figure 3. Green bottle fly 6
Figure 4. Brown garden snail 8
Figure 5. Convergent ladybeetle 8
Figure 6. Common beneficial insects 9 •
Figure 7. Elm leaf beetle egg parasite 11
Figure 8. Aphid parasite 12
Figure 9. Parasitized aphids 13
Figure 10. Two-spotted spider mites 15
Figure 11. California oakmoth and parasite 16
Figure 12. Cabbage maggot 18
Figure 13. European earwig 18
Figure 14. Mini-wasp aphid parasite 21
Figure 15. Ant-aphid relationshp 25
Figure 16. Greenhouse white fly 26
Figure 17. Bees and wasp 28
Figure 18. Cutworms 29
Figure 19. House rat 31
Figure 20. Cat flea 32
Figure 21. Elm leaf beetle 34
-3-
-------
COMMON SENSE PEST CONTROL FOR THE HOME AND GARDEN
Is it possible to reduce damage and annoyance from insects and other pests
without relying exclusively on poisons? Yes, it is, but to do so successfully
you need some information and some patience. This pamphlet can help you with
the first, if you are willing to supply the latter.
Specific pest problems used here to illustrate pest management approaches
are drawn from the Central California coastal and valley urban areas. However,
the general strategies suggested should be useful anywhere.
I. What Controls Insects "Naturally"?
Many insect populations are capable of expanding very rapidly. For example:
the common housefly (Figure 1) can lay one thousand eggs in a season. If one
hundred flies occupy one cubic inch, then in a single summer one pair of flies
might produce enough offspring to cover the planet with a layer of insects four
thousand feet thick. This has never happened because insects, like all animal
populations, are under natural control. The most important of these are climate
and weather, habitat and food, disease, and predators and parasites.
Climate is the long-term overview of temperature and humidity changes in a
region. Weather is its local and short-term variation. Extremes of heat and
cold, of rainfall, dew and fog, can limit an insect population as well as in-
fluence its seasonal distribution. For example, whether the tomato hornworm
(Figure 2) is a pest in your area may be due to whether your climate is favorable
(valley) or not (coastal). But whether the outbreak is early or late in the
season, and to some extent how large it is, may be a function of the weather
that particular year.
With many insects, warm weather increases the speed with which they mature
from larvae (the young form) to adult, while cool weather will retard it. Thus
weather can influence how quickly a population can build up. Green bottle flies
are a good example (Figure 3). With ample food the flies can go from egg to
adult and be ready to mate and lay new eggs in as little as six days when the
temperatures are over 95° F (35* C). Thus a generation can easily mature in
the garbage can between refuse collections, without the householder being aware
of it, particularly if only once per week garbage collection occurs.
Habitat and food may be important limiting factors upon a pest population.
For example, in some areas the ash aphid, Prociphilus fraxinifolii, common on
Modesto ash trees, may prefer to live in the sucker growth around the base of
the tree as well as within the inner canopy. When these suckers are pruned
away, the remaining population of aphids in the tree may be so small as to be
rarely noticed. On the other hand, if the main outer branches are severely-
pruned in such a way as to encourage sucker growth, the ash tree may appear to
have suddenly developed an aphid problem as these insects multiply in their
favored habitat.
The actual nutrient balance within the plant may affect the insects also.
Deciduous tree insects, such as the aphid we have just described, may go through
- 4 -
-------
Figure 1. The common housefly, Musca domestica develops in
decomposing organic matter such as garbage and
pet feces.
Figure 2. Manduca (Protoparce) quinquemaculata, the tomato
hormworm and its close relative M_. sexta, the
tobacco hormworm frequently occur in the same
gardens throughout North America. The hornworm
likes warm summers and is rarely found where
the weather remains cool as along the northern
California coast. Both species of hornworms are
often found with attached larvae or cocoons of
the parasitic mini-wasp, Apanteles congregatus,
a natural enemy of these caterpillars.
-5-
-------
Figure 3. The green bottle fly, Phaem'cia sericata,
develops in garbage as a larva and also
feeds on materials like dog manure as an
adult.
-6-
-------
two population peaks each season responding to the two times when nitrogen is
highest in the foliage - in the spring, when the leaves first unfold, and in
the fall, when they are ready to drop. Aphids may be unintentionally encouraged
through over-use of nitrogen fertilizers in the home garden as well. Nitrogen
is used by the aphid to form new tissues and also in producing young. Thus the
high nitrogen nutrient levels mean higher aphid populations.
Another local common pest, the brown garden snail, Helix aspersa (see Figure
4), may also be encouraged by increasing its favored habitats such as beds of
ivy and succulents that provide a humid cover. It likes to lay its eggs under
boards lying on the soil. If these are used to provide dry passageway over
muddy areas, dry sawdust should be placed beneath them to discourage snail (and
slug) breeding there.
Disease is common to all animals and, just as with humans, crowding of large
populations may encourage the rapid spread of pathogens (disease-causing organ-
isms). Some bacteria and viruses may cause diseases in insects, and a few have
been produced commercially and registered for use. A number of insect diseases
are caused by fungi. Raising the humidity of the immediate environment may help
their spread. Mulches at the base of elm trees, for example, may encourage mor-
tality by fungus disease among the elm leaf beetles when the larvae come down
to the base of the tree to pupate (as when a butterfly forms a cocoon). Water
washing to remove sticky honeydew secreted by large aphid populations may also
encourage outbreaks of fungal diseases because such disease-causing organisms
are favored by high moisture levels.
Predators and parasites, the natural enemies of plant-feeding insects, are
very important in controlling pests. If you want to be able to manage such
garden problems without using pesticides you should learn to recognize some
of the common beneficial insects in your area.
Predators are usually larger than their prey and tend to eat many of them.
Ladybird beetles, ladybugs (such as Hippodamia convergens) are the best known
of these (see Figure 5). Many people do not realize that there are almost 150
species in the San Francisco Bay area alone and four hundred in the nation as
a whole. Some are very particular about what they eat. For example, a commer-
cially available lady beetle, the mealybug destroyer, is a specific predator of
injurious mealybugs.
The convergent ladybeetle (Figure 5) is widely available commercially and
often bought by home gardeners for aphid control. This is the beetle that flies
to the foothills of the Sierras and other streamside hibernating sites where it
congregates in large numbers and is easily scooped up by the millions. Unfor-
tunately, many people do not know that ladybugs so gathered, without subsequent
treatments, will fly to burn off stored fat deposits. Thus, when released, the
beetles fly to another area. Frequently, just at the time of purchase and re-
lease of the hibernating beetles, the migrating ones are flying into yards and
are mistaken for those released. If you decide to purchase ladybeetles, be sure
that they are described as defatted.
Other important predators are green and brown lacewings, hover flies, rove and
ground beetles and various predatory "bugs" (Figure 6). The important thing about
-7-
-------
Figure 4. The brown garden snail, Helix aspersa
was introduced into California in the
1850's as a food source. Today it is
widely poisoned as a U.S. pest while
at the same time, cooked and sauced,
it is being imported from Europe as
a gourmet delicacy.
Figure 5. The larva and adult of the convergent ladybeetle,
Hippodamia convergens .which occurs throughout
North America. The twelve black spots are not
always distinct or present.
-8-
-------
Figure 6. Some common benefici?.! insects of the home garden:
' top left, rove beetle; bottom left, ground beetle;
top right, adult flower fly (also called hover fly
and syrphid fly); bottom right, flower fly larva
attacking an aphid.
-9-
-------
these insect predators is that if they are not naturally restricted in their
diet to feeding on a specific species of pest, they will tend to be oppor-
tunists, moving from species to species, feeding on whatever is most abundant
at the moment. Thus, although they are helpful in reducing pest population
sizes, they may not reduce the numbers of pests to an acceptable level unless
sufficient numbers are present. One" way to accomplish this is to intention-
ally release them for that purpose. Some insectaries are producing such
insects and many species are now commercially available.
Parasites, on the other hand, are usually smaller than their prey. The
parasitic natural enemies of insects are sometimes called parasitoids because,
although their way of life resembles that of true parasites, unlike the latter
they kill their host. They may consume only one individual during their life-
time. Many are members of the order Hymenoptera, along with the bees and wasps.
Often they look like minute wasps or "mini-wasps". Parasites can offer good
control of an insect population, even when the latter is present at very low
densities because they are restricted in the number of species they can attack.
Although these mini-wasps are very common, they are very small and most people
are unaware of them; consequently, they usually don't have common names.
A common life cycle starts with an adult female mini-wasp laying her egg
inside of or on a specific stage of another insect. For example, the elm leaf
beetle has one parasite that lays its eggs in the eggs of the beetle (see Figure
7), and another one that lays its eggs in the pupa (cocoon stage). These para-
sitoids do not attack other insect species. An aphid parasite may feed upon and
thus kill several aphids during the process of selecting one in which to lay its
egg. These parasites may operate like predators and wound their host with their
egg-laying stinger (or ovipositor) without depositing an egg (see Figure 8).
They then feed on this wound, killing their host. Sone parasites lay many eggs
witin'n or on the body of their hosts; others lay only one. In any case, the egg
develops into a maggot-like larva which begins to eat away its host, sooner or
later causing its death. After killing its host, the larva of the mini-wasp
changes into a pupa. Aphid parasites may do this within the aphid itself. These
dead parasitized aphids can be easily spotted in a colony of living ones. They
are usually a slightly different color, stiff and shiny. Other parasites may leave
the dead host to spin a cocoon somewhere nearby (see Figure 9).
Within the pupal case, the insect changes (metamorphoses) from maggot-like
to wasp-like adult form. With some species of parasites the newly emerged female
adults must find males to mate with before they can lay fertile eggs to start the
cycle over again. With others mating is unnecessary, and males are unknown or
rarely found.
Through understanding something about the many natural controls of insect
and other animal populations, new possibilities for managing pests may become
apparent.
-10-
-------
Figure 7. The eulophid egg parasite, Tetrastichus galerucae,
only attacks the early stages of the eggs of the
elm leaf beetle.
-11-
-------
Figure 8. The aphelinid, Mesidiopsis sp., operates as a
parasite or a predator on a number of tree aphid
species. As a parasite it lays its egg within the
aphid. The egg develops into a larva which eats the
aphid from the inside. As a predator, Mesidiopsis
punctures the live^ephids and sucks out their juices,
-12-
-------
Figure 9. The parasitized aphids or "mummies" can commonly
be seen in colonies of live aphids if you look carefully
They are usually shinier and rounder than the live
aphid, a different color (tan, white, or black) and
stiff appearing.
-13-
-------
II. If Natural Controls Are So Great, Why Don*t They Work?
You might feel inclined to ask this question if you are currently battling
some damaging or annoying pest problem. The answer is that natural controls dp_
work, all the time. In fact, the numbers of species of potential plant-feeding
insects are so great that if most of them were not under good natural control,
they would have long ago denuded the earth of plant life, making their further
survival, along with our own, impossible.
However, at certain times, in certain places, specific animal populations
may grow so large that they become a problem. What can account for this?
One reason is that sometimes their parasites and predators cannot find them.
Inside the house or greenhouse, for example, aphids, mealybugs, whiteflies or
spider mites (see Figure ip) may all become a problem. This can often be solved
by setting the plant outside for a few days until the natural enemies find the
pests and control them.
Since all animal populations tend to fluctuate, rising and falling in num-
bers due to the factors we have mentioned above, occasionally a native insect
will become numerous enough outdoors during one or more seasons to cause aes-
thetic or economic damage. Then the outbreak will subside due to natural controls
and the insect may hardly be noticed for a few or many years, after which another
outbreak may occur again. An example of this sort of seasonal fluctuation is the
periodic rise of the California oakworm (see Figure 11), believed by many to be
a native insect. It does have parasites, predators and pathogens which usually
keep it in check as long as the trees are not treated routinely with pesticides
which kill off these natural enemies of the caterpillar.
Even with these natural controls, however, the populations periodically
rise to great numbers and are capable of completely denuding a tree of its
leaves. When this happens near the house, people can become upset, either be-
cause they expect the tree to remain green, or they object to the sight of the
caterpillars and their droppings. This generally occurs in the dry season, thus
reducing the water loss by these trees. (Water loss by plants is principally
through the leaves.) Furthermore, the caterpillars process the leaves, which
are very slow to break down, leaving behind their own droppings which release
nutrients back to the tree when the winter rains come. Thus, periodic defolia-
tion of native oak trees may be more beneficial than harmful.
In comparison with these noticeable fluctuations in the size of native
insect populations from season to season, the invasion of a foreign insect
may result in regular high populations every year. The invading insect has
usually left its most important natural enemies behind in its area of origin.
Although in some cases predators and parasites of closely related insects may
consume some small number of the new invader, the absence of controls that are
specific to it usually permits the latter to reach population levels regarded
as aesthetically or economically damagina.
Some examples of such pest animal invaders of annoyance to California
gardeners are the brown garden snail, the elm leaf beetle, a number of common
tree-feeding aphids, such as those on silver maples and crepe myrtles, the newly
invaded aphid on tulip trees, and a variety of insect pests of common garden
-14-
-------
*»•
r^WSHDBNw^ •
••;•<,
f. tv V&P^?' '
HsK-'
Figure 10. The two-spotted spider mite, Tetranychus urticae,
lives within small silken webs, makes very small
feeding wounds on the leaves and gives them a
speckled appearance. Mite outbreaks usually develop
in response to plant stress or disruption of the
mites' natural enemies, which are predominantly other
predacious mites.
-15-
-------
Figure 11. The adult (right) of the California
oakmoth, or oakworm, Phrygam'dia
californica. sometimes occurs in
large numbers which may be unnecessarily
alarming. The above pictures the
most important parasite, Itoplectis
beherensis stinging the pupal (cocoon)
stage of this insect.
-16-
-------
vegetables such as the cabbage butterfly, the cabbage maggot (Figure 12)
the corn earworm and others. The common household cockroaches and several
other important indoor pests are also introduced to this continent from the Old
World. The Argentine ant, a frequent house invader when the first fall rains
flood its outdoor nests is, as its name suggests, from South America. All
these insects have in common that fact that they have escaped all or most of
their natural parasites, predators and pathogens.
There is another factor that may account for specific high pest populations
on a particular plant: the greater genetic susceptibility of some domesticated
plants compared with other closely related horticultural strains or a wild an-
cestor. A good example in this area is the Modesto ash tree. This is a strain
or cultivar,propagated vegetatively (by taking cuttings) from a single tree in
Modesto, California. It is more susceptible to both the ash aphid and ash
anthracnose (a disease) than other cultivated ashes that resemble it closely,
or the native ashes of California and Arizona to which it is believed to be
related. A similar phenomenon is seen in agriculture. In general, as vege-
tables are bred for human consumption, a number of qualities are eliminated
that might have served to discourage insect attack in the wild state, for
example, strong oils, terpines, resins or hairyness.
Potential pest populations also may be encouraged, or their natural enemies
discouraged, by attempting to grow a particular variety of plant in an environment
not suited to it. It may simply be too hot or cold, wet or dry for that plant
in comparison to its native home. Stressed by an unsuitable environment, the plant
may be more susceptible to insect attack or less able to outgrow damage when it
occurs.- An example would be the susceptibility of the Monterey pine to pine pitch
moth when planted in hot, sunny interior locations unlike the cool, foggy coast
to which it is native. Bark beetles offer another example of the influence of
environmental conditions. Water-stressed trees are more susceptible to damage
from these insects. The European earwig (Figure 13) is an omnivore, feeding on
other insects as well as plants. They may cause greater damage to seedlings in
unmulched gardens, since with bare earth between the plants there is less other
food for them.
Free water from dew, sprinklers, etc., and nectar and pollen from shallow-
throated flowers, are necessary for many parasitic insects, particularly tiny
ichneumonid wasps, which parasitize many caterpillar species. Without this
liquid and protein the lives of many natural enemies are shortened and con-
sequently pest numbers may rise. Horticultural settings usually are contrived
with a mixture of plant species from many continents brought together in close
proximity, often with insufficient consideration of their individual native
requirements. Thus it is not surprising that a stable mix of insect and other
wildlife populations is difficult to achieve.
Finally, the methods used to deal with the pest may themselves cause the
problem to become worse or cause entirely new problems, as described in the
next section.
-17-
-------
Figure 12. The adult cabbage maggot (Hylemya brassicae)
is a fly that lays its eggs near the base of
plant members of the cabbage family. When
the eggs hatch, the larvae tunnel into the
plant roots. This drawing shows a predatory
rove beetle in the genus Coprochara feeding
on the larva.
The European earwig, Forficula auricularia is
an accidentally introduced plant pest in many
parts of the world. It is also a beneficial
predator feeding upon a variety of insects,
including fleas which it readily captures.
The name earwig refers to its ear-shaped
wings. It does not harm humans.
-18-
-------
III. What's a Safe Pesticide I Can Use?
When pest problems become intolerable (and sometimes even when they are
in no danger of becoming so), the first thing many people want to do is use
a pesticide. While theoretically anything that kills a pest might be so
designated, usually the tern is used to refer to a chemical compound that will
kill the target organism when the poison is eaten, inhaled or absorbed through
the skin or cuticle. Pesticides may be referred to as insecticides, herbicides,
fungicides, rodenticides, miticides, algacides, molluscicides, etc., according
to the target pest they are used against. With an increasing awareness among
the general public that these compounds can affect humans and other animals
as well, people are asking, "What is a safe pesticide to use?" To understand
the answer it is necessary to know something more about how pesticides are
misused.
The best known of the problems associated with too heavy reliance on
pesticides deals with the direct or acute "residue" effects. Warning state-
ments on the label alert users of potential dangers; this is why it should be
read thoroughly and directions followed carefully. While most people think of
pesticide danger from ingesting the poison, some can be harmful if absorbed
through the human skin. Dermal or skin exposure can occur during application
of the pesticide, or afterward, through contact with sprayed surfaces. When
the pesticide is sprayed into the air, it may cause harm if it is inhaled.
Materials used on ornamental plants, such as roses, may be quite unsuitable
for use on vegetables because of the danger of eating the poison along with
the food. Carefully read the EPA registered label to find out on what^ orna-
mental or food plants the material may be used, the proper dosage and other
precautions.
The 1050 is the rating used to describe the degree to which a particular
compound is directly poisonous. It refers to how much is needed to kill fifty
percent of the test animals (usually rats) expressed in terms of milligrams of
poison per kilogram of body weight. Thus, the higher the number, the less
toxic the compound might be considered.
The toxicity of a compound is independent of whether it is derived directly
from plant sources.(the "botanicals"), or whether it has been synthesized in
the laboratory from petroleum. For example, the pesticide pyrethrum has an
oral rat LD$Q of 200 mg/kg, suggesting that it might be safer to handle than
nicotine with an 1059 of 50-60 mg/kg, yet they are both botanicals. On the
other hand, a laboratory synthesized compound, malathion, for example, has an
1050 of 2800 and consequently has been regarded as less toxic to humans and
other mammals.
A guide to the toxicity of any particular product can be found on the front
panel of the EPA registered label. The most toxic compounds are those with an
oral toxicity up to 50 mg/kg, or a dermal 1059 up to 200 mg/kg, and must bear
the signal word "Danger". A compound with an oral LDso from 50 through 500
mg/kg must carry the signal word "Warning". Less toxic compounds with toxicity
ratings above these latter must be indicated by the word "Caution". Many of the
most hazardous compounds have been withdrawn from the market and are only avail-
able to specially trained personnel and under specific circumstances. The active
- 19 -
-------
ingredient is listed on the front of the label. There are reference books that
can give you the LDso and other information you might wish to have about each
compound (see Bibliography).
In recent years, however, it has become apparent that the LDso is not the
whole story, as far as human health is concerned. Some of the materials that
were once considered relatively non-toxic because of their high LDgn's are
now suspected of causing birth defects, genetic defects or cancers that develop
many years after the original exposure to the compound. Furthermore, very
little is known about the synergistic effect of some of these materials, that
is, the effect they have when combined with other compounds, e.g., pesticides
along with the common air pollutants of the cities.
In addition, when considering how safe a material is, one has to look at
its effects on the environment. Inevitably, in the use of most poisons, con-
siderable amounts fall upon non-target organisms, plants and other animals.
Since a healthy garden is teeming with life, both above the soil and within it,
there can be all kinds of undesired side effects from using a particular material.
Fungicides used against a plant disease may fall upon the ground and inhibit
the growth of beneficial fungi, called mycorrhyzae, associated with plant roots
and important in helping the plant to obtain nutrients. Decomposer organisms,
which break down dead plant and animal litter so that the nutrients are once
again available for plant growth, may be affected by insecticides used on
plants that fall on garden soil.
Some pesticides have been found to accumulate in food chains. That is,
small amounts of poison distributed over plants or plant-eating animals are
concentrated in the bodies of organisms that eat them, until finally at the
top of the food chain, the animals may be sickened directly or suffer impaired
ability to reproduce. In one classic case, small fish absorbed pesticides from
contaminated waters through the microorganisms they fed upon. These fish were
fed upon by other fish and the brown pelican, a fish-eating bird at the top of
the food chain, suffered a serious population decline due to the effects of
these accumulated poisons. This is one reason why a whole series of long-
lasting compounds, starting with DDT, were withdrawn by the Federal government
from regular use by the public. Since humans are at the top of numerous food
chains on this planet, the long-term health consequences of using these pesti-
cides were feared. DDT is an example where relying upon the direct toxicity
of a pesticide, as expressed as LD5Q, is inadequate, particularly in deter-
mining if the compound will biomagnify, as food chain contamination has come
to be called.
The above described direct effects of pesticides upon the health of humans
or other non-target animals have been well publicized. Less well-known are the
ways in which injudicious use of these materials can disrupt the management of
pest populations. The most obvious example of this is when the oesticide
inadvertently kills off the natural enemies of the pest (Figure 14), allowing the
latter to resurge to even greater numbers than before treatment. A second pesticide
treatment may cause an even quicker pest return until you are treating repeatedly
with less and less long lasting results. This can easily be demonstrated with
aphids on roses or with whiteflies on many ornamentals and vegetables. It is
never possible to kill off all of the pests, and even if it were, there are al-
-20-
-------
Figure 14.
This mini-wasp is a parasite of an aphid.
It lays its eggs in the aphid and later
emerges from the mummy. When unmated,
only males develop from its eggs but when
mated both sexes can develop.
-21-
-------
ways others that can fly Into the area. Since the parasites and predators of
the pest insects are fewer in number than their prey, usually slower to repro-
duce or_.di_sp_erse, and sometimes more.susceptible to the poisons, it is easy to
see how a pesticide treatment might actually make the problem worse"instead of
solving it. The insecticide carbaryl is an example of a compound that is
particularly harmful to many insect parasites.
With repeated pesticide exposure, a resistant population of pest organisms
may develop. This is because each time a spray is used, some of the insects
surviving to reproduce the next generation are those that received a dose but
were somehow able to detoxify the poison. With each treatment their numbers
increase compared with those that survive by merely managing to avoid contact
with the poison. Gradually it becomes harder to reduce pest numbers by spraying,
People often report increasing the frequency of treatment and the strength of
the dose, yet the insect populations, such as cockroaches or whiteflies, are
back again sooner and in greater numbers than before. When dealing with pests
that can transmit diseases to humans or domestic animals, such as mosquitoes
or rats, two pest animals among which resistance to certain pesticides has
become a problem, the consequences can be very serious. This is one of the
best reasons for using pesticides only as a last resort after all alternative
methods have been tried. That way, when a pesticide is necessary, it is more
likely to be effective.
Although one is usually conscious of one or two potential pest problems
on most garden plants, in reality there are a large number of other species
of plant-eating insects in every environment that are rarely noticed because
they are under good natural control by their specific parasites and predators.
Thus, there is always the danger that the use of a poison against a pest
problem will kill off the natural enemies of other potential pests of which
one was not aware. In many cases, these latter animals may suddenly cause
secondary pest problems as their numbers increase in the absence of control.
In some cases the new pest may cause as great or greater problems than the
pest that initiated the original treatment. For example, when spraying oak
trees for the California oak moth using a carbamate, severe mite outbreaks
may occur.
- 22 -
-------
IV. What Should I Do?
The Theory
In place of relying exclusively on chemical tools to manage pest problems,
the safest and surest approach is to learn more about the animal you intend
to manage and use a series of strategies to deal with the problem. One of
these strategies is to determine just when it is necessary to act at all.
Since an abundance of insects and other wildlife is desirable to obtain a
natural balance in the garden, the wise gardener soon learns that the sight
of a plant-feeding insect, or even many of them, is not by itself reason to
panic. The pest insects must be present to keep their natural enemies around.
Signs of insect presence - leaves chewed here or there, an occasional imperfect
blossom - must be accepted as a natural complement of any healthy garden
environment. It is only when the damage is about to become truly intolerable
that action must be taken. Then, the least disruptive strategies applied just
where needed will insure that the balance is restored once again with minimal
side effects in terms of human health or the general environment.
The approach described here is sometimes referred to as Integrated
Pest Management or IPM. The potential pests and their natural enemies are
observed on a regular basis (called monitoring, scouting, inspecting or
checking) and decisions are made about what strategy or combination of
strategies to use based on these observations. The actual strategies may
involve plant selection, habitat manipulation, cultural or physical controls,
methods to enhance beneficial insects already present or to release more
into the area. In conjunction with the above strategies, the use of an
appropriate pesticide confined to a particular spot where no other method
is adequate to prevent intolerable damage may be warranted.
Some Specific Examples
Snails:
These strategies can be orchestrated into an Integrated Pest Manage-
ment program against the brown garden snail. This snail is a native of
Europe, deliberately introduced as a food animal, and presently a serious
pest along the Pacific Coast and elsewhere. An effort to manage the pest
should begin with habitat modification. Since snails breed in moist shady
conditions, in beds of ivy, on certain succulents, and where boards rest upon
wet soil, these areas should be reduced as much as possible. Fine dry saw-
dust can be placed under boards used as walkways in muddy areas in the garden.
Some gardeners have reported a substantial reduction in damage to seedlings
from encircling them with a tin can barrier. The can is opened at both ends
and pressed down into the soil around the seedling. If the soil is moist,
it can be pushed in an inch or so. This offers a fairly effective barrier
to passing snails while the plant is young. Another physical barrier can
be made with aluminum screen.
Overturned clay flower pots make effective traps if they are set close
to the shady side of a plant and the ground surface is sufficiently irregular
to permit the snails to glide in under the rim. During the warm part of the
- 23 -
-------
day the snails will collect inside the pots from which they can be removed
periodically and killed. In general, handpicking is one of the safest and
surest methods of ridding many animal and plant pests from a small area.
Snails and slugs are ideally susceptible to this method of control since
most are large enough to pick up or squash easily. If you are squeamish,
wear garden gloves. When collecting snails for eating, feed them for a few '
days on clean vegetable material or corn starch to clear out any garden grit
from their alimentary system before cooking. They are regarded as a delicacy
in many areas of the world.
Finally, if these non-toxic methods do not give a sufficient degree of
control, you may wish to make judicious use of a bait. An effective bait
contains the active ingredient, ferrous ammonium sulfate. It degrades to
a fertilizer. The active ingredient in the most commonly available bait is
metaldehyde. Metaldehyde (sold under various trade names) is an organo-
phosphate. Since it is poisonous to dogs, if they are allowed in.the area,
care should be taken to place the bait inside a receptacle to which they
cannot get access, for example, a flattened tin can placed among the plant
stems. In any case, the poison should be. used only during the part of the
season when the" damage is severe and confined to those areas of the garden
where the plants are seriously susceptible. The pellets may last longer than
the powder. Apply pellets after rains or after watering. Excessive moisture
reduces their effectiveness. There is always the danger that where large
amounts of the poison are used, a resistant local population of snails may
develop. Metaldehyde resistance has been reported and thus this bait al-
ready may be useless in your area. In any case, read the directions on the
EPA registered label before using any pesticide.
A regular checking of the garden for damage while removing snails from
the flower pot traps is one way to monitor the size of the snail population
and determine where additional efforts are needed. The combination of
strategies, habitat modification and plant selection, barriers and traps,
handpicking and baits, together with monitoring combine to make an integrated
pest management program against the garden snail.
Aphids. Mealybugs, Scales, Whiteflies:
These insects excrete a sugar-protein mixture called honeydew. Honey-
dew was probably the original "manna" from heaven of the Bible and may drip
from the trees when producer populations are heavy. A black "sooty mold"
may grow upon the honeydew, like mold in a jelly jar.
In controlling these honeydew producers, exclude ants whenever possible.
Ants will protect the honeydew producers from their natural enemies in order
to harvest the sweet sugar-protein secretions (see Figure 15). Trees and shru'rs
with a single or few stems can be ringed with a sticky material such as StickemR
or TanglefootR (not a poison, but an adhesive). Caulking their entrance holes
with outty will exclude ant invaders from house plants. Ant baits are sometimes
effective in reducing ant activity on aphid or scale infested plants, but it is
essential to hide the bait containers away from children who might be tempted to
play with them. Available baits frequently don't work anainst the Argentine ant,
so any materials used should be carefully observed to see if they are effective.
-24-
-------
NCIC/OTS CHEMICAL LIBRARY
4°1 M ST., S.W., TS-793
WASHINGTON, D.C 20460
Figure 15. Ants frequently harvest honeydew from aphids
(as well as from other honeydew producers) and
actively protect them against their natural enemies.
Thus protected, the aphid populations can increase,
which in turn produces overabundant honeydew. Honey-
dew can be used as a food, and is believed to be the
"manna" of the bible. It is still collected from
certain scale insects in the Middle East and sold as
a candy in the bazaars.
-25-
-------
^;&^;v. &&;•.
..
Figure 16. The greenhouse whitefly, Trlaleurodes vaporarlorum
(above) looks like a tiny white fly in the adult
stage. As a developing larva, it looks much like a
scale - which is attached to the leaf and cannot move.
Below is the adult Aphelinid parasite Encarsia formosa
which is used to control white flies in Europe.
-26-
-------
Water washing the plant is very useful in cleaning off aphids and their
honeydew, especially early in the season when the aphids are young, few can
fly and most of their natural enemies have not yet arrived. Water washing at
this time will not harm the natural enemies. Heavily affected parts of a plant
may sometimes simply be pruned off and composted. Those colonies clustered on
plant tips can be crushed by hand. During the warm season , house plants can
be set in a sheltered area outside where the natural enemies may find the pests.
Indoors, house plants can be inverted over a basin and washed with soap and
water to clean off aphids, while scales and mealybugs can be rubbed off with
a cotton swab dipped in alcohol.
In the greenhouse, green lacewings (Chrysopa carnea) can be bought and re-
leased against aphids. Whiteflies, another indoor pest, have a parasite,
Encarsia formosa, specific to them which is also available commercially.
(See Figure 16.)
Bees, Wasps:
Both bees and wasps are very beneficial (Figure 17). Bees pollinate our crops
and the common garden wasps are important predators of caterpillars and other
insects. Avoid wearing perfumed cosmetics or using soaps and shampoos with
strong odors if you must move around where bees are abundant and active.
Yellowjackets can be lured away from the picnic table by bits of tuna fish,
raw liver, or cups of sweetened fruit-flavored soft drinks placed at a safe
distance. If you are highly allergic to insect stings, consider getting
treatments that desensitize you.
Caterpillars:
When the caterpillars are large and easy to reach, as with the tomato
hornworm, handpicking is the easiest solution. More thorough searches are
needed for the cabbage worm. Large wasps and yellowjackets should be pro-
tected when possible as they are important in controlling many common cater-
pillars on vegetables and ornamentals. Searches at night with a flashlight
are frequently necessary when suspecting cutworms (see Figure 18). Pruning
out tent caterpillars in trees is effective.
B^., short for Bacillus thuringiensis, is a useful tool in managing
high populations of a number of caterpillars, common and annoying in this
area, such as oak moth, tent caterpillar, and fruit tree leaf roller. It
is a naturally occurring disease of these insects, produced commercially for
many years in this country, and sold under several trade names. It is in
many ways preferable to other common materials used against these insects be-
cause it will not harm their natural enemies and is non-toxic to people, pets,
other domestic animals and wildlife. Thus it cannot cause outbreaks of other
pests through killing off the beneficial predators and parasites.
B^. is a living material that must be kept in a cool dry place. It
will store the longest in the wettable powder form. It should be applied to
the leaves of the plant at the time when the caterpillars are large enough to
be eating through the leaves. This increases the likelihood that the larvae
will consume a toxic dose. When spraying the material on the olant it is
- 27 -
-------
Figure 17. Above: bees on their combs. The large
one is the queen. Below: a predacious
wasp. All bees and wasps are beneficial
yet can sting if provoked.
-28-
-------
Figure 18. Suspect cutworms (the larva of a moth) when
seedlings have been snipped off near ground
level. Search for them at night on the plants
or in the day curled up nearby in the mulch.
-29-
-------
easy to miss coating both sides of the leaves and, when the caterpillars are
young and feeding only in a restricted area, sufficient numbers may not en-
counter enough B^. Since the B..t_. must be eaten by the insect to have an
effect, and the adult moths do not eat the leaves, there is no point in spraying
when the moths are flying. Furthermore, there is no way to know at the time
when the moths are laying eggs whether a sufficient number of the caterpillars
will ever live long enough to cause any damage. During most seasons in most
areas their many natural enemies will keep the numbers of caterpillars down
to where the damage, if noticeable, is still tolerable.
Follow directions for use on the particular EPA registered label for
timing and method of treatment, insects controlled and plants to which a
B^.t^. product may be applied.
Cabbage Maggots, Garbage Flies:
Exclusion whenever possible is a useful defense against adult flies.
Use window screens on the house. In the garden use screened enclosures to
protect the cabbage family plants against the fly whose young is called the
cabbage maggot. Once flies are in the house, the fly swatter and the string
of fly paper are still the best methods of killing the flies and protecting
your health at the same time. Ultimately, however, preventing the production
of flies is the key to successful management.
Common house flies develop in organic wastes. In warm weather the average
garbage can may produce over a thousand flies a week. The answer is to manage
organic wastes properly. Place kitchen garbage in tightly closed containers
until it is picked up through the city refuse collection. Or, better yet, learn
to store and compost it properly so that smells do not attract adul.t flies to
lay eggs and so that the high temperatures of the compost kill any eggs and
larvae tha't are present. For further information on composting methods suitable
for use in urban areas, see the Bibliography.
Cockroaches, Ants, Food Moths, Fleas, Rats:
The first step with all these pests is exclusion. Indoors, place food
in jars. Use tops that seal with an inner liner in the cap or a rubber ring.
Caulk up cracks through which ants enter and in which cockroaches hide.
Caulking compounds will handle the large cracks, latex paint the finer ones.
Use cement, screen or hardware cloth to close off all gaps around pipes and
electric or other lines where they enter the house. Similarly screen off with
hardware cloth all ventilation or other holes in eaves in attic and basements
through which rodents can enter.
Outdoors, place garbage in cans with tight lids, stack wood neatly and
clean up junk heaps where rodents may nest. Do not leave cat and dog food
out all day. (Figure 19) Feed as much as the animal will eat at one time
and remove remains until the next feeding. If your compost is not kept in
a bin and turned regularly so that it heats up, use only garden debris within
it and avoid adding kitchen garbage. If you do use a hot compost for managing
organic wastes, then add to it any dog manure you may find. Such droppings,
when left uncomposted, can provide food for rats.
- 30 -
-------
Figure 19. A young rat, Rattus rattus feeding at the
pet food bowl. Rats gain entry to the house
through various openings such as around pipes,
electric lines and sewers (through toilets).
-31-
-------
Figure 20. Usually it is the cat flea, Ctenocephalides
felis that is pestiferous on humans and dogs.
The dog can also have the dog flea, C_. cam's,
Fleas are vectors of disease. The oriental
rat flea can transmit bubonic plague and
typhus, the dog flea, tape worms.
-32-
-------
Fleas (Figure 20) are usually only a serious problem in the late summer
and early autumn. Prepare for this by doing your spring cleaning in late
summer. Thoroughly vacuum and wash all floors, rugs and other surfaces to
which your pets have access. Ideally the contents of the vacuum cleaner bag
should then be composted, burned, frozen, or emptied into a garbage can.
This will pick up both adults and developing larvae as well as remove their
food sources. Giving a dog a combing or bath also is a good idea. If the
infestation becomes so bad that you feel you must use a flea collar on your
pet, use it only during the time populations become intolerable, removing the
collar and storing it in a small air-tight jar in the freezer until the next
time it is used. Flea collars send an insecticide into the air that disrupts
transmissions of nervous signals. Although this vapor is invisible, remember
that it is being emitted and is a poison. Such products should be approached
with caution.
Dutch Elm Disease - The Difference Between Elm Bark Beetles and Leaf
Feeding Beetles
The Dutch Elm Disease is caused by a fungus which came originally from
Europe, spread slowly across the country and reached California in 1975.
The most common symptoms of the disease are a sudden paling of the vegetation
on the uppermost limbs, and death of those limbs and eventually the entire
tree. The fungus is spread by elm bark beetles that live just under the bark
of certain species of elm trees when they are weakened or dying. During a
brief period in each generation, the elm bark beetles fly to and feed on
healthy non-diseased trees. It is during this time that the fungus spores
carried on their bodies may brush off and infect other elms. The beetles
then return to the weakened or dying trees to lay eggs. There may be two
full generations per season. The best approach is to make sure that all dead
or dying elms or elm branches are carefully removed and destroyed. All cut
elm wood should be burned immediately, or the bark removed, so no sites re-
main where the beetles might lay their eggs. Beetles in removed bark from
diseased trees should be destroyed.
Do not confuse the elm bark beetle, which is rarely seen on the leaves,
with the elm leaf beetle (Figure 21 ) which is common and highly visible on
many elms and can cause serious defoliation. The latter beetle, an invader
from Asia, lays its eggs on the leaves, has several generations per year and
at the end of the larval stage, crawls down the tree to pupate around the base.
An active project to control this latter insect using its natural enemies is
presently underway in California. The elm leaf beetle is not a sign that a
tree has Dutch elm disease.
You should become aware of dead and dying branches and/or a generally un-
healthy look to the leaves of your elm, and, if you suspect Dutch elm disease,
call your county agricultural commissioner's office or the street tree depart-
ment of your city and ask for guidance on managing the situation.
- 33 -
-------
Figure 21. The elm leaf beetle, Pyrrhalta luteola, feeds
on the leaves of most elms. Probably originating
from the Middle East, it is a major pest problem
in Europe and the United States.
-34-
-------
V. Summary of Control"Method's"
To develop a sound pest management program for your home and garden,
first consider the alternative strategies in the following order:
1. Plant selection. When possible, plant varieties that are somewhat
resistant to the potential pests in your area.
2. Cultural controls. See if modifying your watering, fertilizing,
pruning or other methods of plant care will reduce the numbers of pests, or
enhance the pests' natural enemies or the plant's ability to outgrow the
damage.
3. Habitat modification". Determine if changing the environment in some
manner will reduce the problem, by either discouraging the potential pest,
or encouraging its natural enemies; e.g., mulches, removing or adding nearby
plants, modifying wind or light conditions, etc.
4. Physical controls. Pick off and kill the pests by hand when possible,
at night with a flashlight or in the very early morning when the insects may be
too cold to move away from your grasp easily. Vacuuming will work for large
congregations at the doorstep or windowsill. Washing and vacuuming will clean
up flea larvae.
5. Barriers. Screens, nets, sticky materials and similar barriers are
frequently appropriate for keeping potential pests out of the garden or the
house or away from specific plants.
6. Traps. The potential pest may be lured into a trap by light, smells,
pheromones (insect attractants), darkness, etc. Observe the behavior of the
animal you are trying to trap, or read something about it.
7. Baits. Baits may be used to bring the potential pest to a trap or to
kill it outright. Poison baits are always preferable to sprays or drenches
since less of the environment is affected by the toxic materials. If they are
properly chosen and placed, the impact on the environment should be minimal.
8. Biological control. Most of the above methods are designed to con-
serve the naturally occurring biological controls already in your environment.
In some cases these may be enhanced by providing habitat, food or water, e.g.,
bird nesting sites, overturned flower pots for ground beetles, etc.
In some cases release of lacewing eggs or larvae, or Tricogramna mini-wasps,
may be helpful to augment the biological controls already present.
If no alternatives work adequately, the damage is severe and you choose to
use a pesticide:
1. Choose the least toxic materials, e.g., water, soap and water, and
pesticides with the signal word "caution" on the label.
2. Choose selective materials whenever they are available, e.g., Bacillus
thuringiensis sprays, or baits against certain caterpillars.
-35-
-------
3. Read the labels of all pesticides carefully, follow the directions
given on how to protect the applicator and the environment, mix only the amount
you will actually need (if you will use half a cup to spray one branch, don't
mix a gallon and spray the yard), and clean up appropriately afterward.
In the last analysis no single technique will solve a pest problem over
the long term. Combinations of techniques used together, timed properly and
called into play when injury levels will be exceeded, is the best approach
known to manage pest problems.
VI. How Can I Get More Information?
An excellent book on controlling insects on house plants is Windowsill
Ecology, by William H. Jordan, Jr., Rodale Press, Inc., Emmaus, Pennsyl-
vania, 18049.
Good books to be consulted by lay gardeners interested in getting bugs
identified are Insect Pests of Farm, Garden and Orchard, by R. H. Davidson
and L. M. Peairs, John Wiley, New York City, and A FieTd Guide to the Insects,
by D. J. Borror and R. E. White, Houghton MiffTin Co., 6th edition.
For information on composting methods that reduce fly production, see
The City People's Book of Raising Food, by Helga and William Olkowski, Rodale
Press, Emmaus, Pennsylvania, 1975.
A detailed discussion on using non-toxic methods to control pests inside
the home, in the garden and in small-scale greenhouses is found in The Integral
Urban House, by Helga Olkowski, William Olkowski and Tom Javits, Sierra Club
Books, San Francisco, California, 1979.
To determine the LDso. the chemical name and other characteristics of
common pesticides, see the Pesticide Index by W. J. Wiswesser, Editor, Entom-
ological Society of America, 4603 Calvert Road, Box AJ, College Park, Maryland,
20740.
The Pesticide Division of the regional branch of the Environmental Protection
Agency can answer many of your questions about the pesticides and their use.
City, county and state health departments can also be contacted.
The local cooperative extension office may be helpful in providing infor-
mation about alternative methods of pest management if specifically requested
to do so. Your local library or city maintenance departments may also be good
sources of information.
- 36 -
-------
VII. Scientific Names of Common Insects, Insect Families
and Other Pests Mentioned in the Text, and Pages Where They Appear
Scientific Names Pages
ants, in general
Argentine ant
aphids, in general
ash aphid
bees
brown-banded cockroach
brown garden snail
brown lacewing
cabbage butterfly
cabbage maggot
California oakworm
caterpillars, in general
crepe myrtle aphid
convergent ladybeetle
corn earworm
cutworm
earwig
elm bark beetle
elm leaf beetle
fleas, in general
food moths
garbage flies
family Formicidae, many species
Iridomyrmex humilis
Aphidoidea, more specifically
Aphididae, many species
Prociphilus fraxinifolii
family Apidae, many species
Supella longipalpa
Helix aspersa
family Hemerobiidae, many species
Trichoplusia rn_
Hylemya brassicae
Phryganidia californica
order Lepidoptera, many species
Melanocallis kahawaluakalani
Hippodamia convergens
Heliothis zea
family Noctuidae
Forficula auricularia
Scolytus multistriatus
Pyrrhalta luteola
order Siphonaptera, many species
e.g., Mediterranean flour moth
Ephestia (Anagasta) kuhniella
usually, Phaenicia sericata
24, 25, 30
17
4, 7, 8, 12, 13
14, 17, 20, 21,
24, 25, 27
4, 17
27, 28
17, 22, 30
7, 8, 14, 23, 24
7, 35
17, 27
17, 18, 30
14, 16, 22
14, 17, 27, 29, 30
14
7, 8
17
29
17, 18
17, 33
7, 10, 11, 14,
33, 34
18, 30, 32, 33, 35
30
4, 5, 6, 30
-37-
-------
Table VII., cont'd.
Scientific Names
Pages
green lacewing
ground beetles
hover flies
mealybugs
mealybug destroyer
mites, in general
mosquitoes, in general
parasitic insects
pine pitch moth
predatory bugs
rats
rove beetles
scales, in general
silver maple aphid
spider mite
tomato hormworm
wasps
whiteflies, in general
family Chrysopidae, more
specifically, Chrysopa carnea
family Carabidae, many species
family Syrphidae, many species
family Pseudococcidae, many species
Crypto!aemus montrouzieri
class Acarina, many species
famly Culicidae
order Hymenoptera, Diptera
and others, many species
Vespamia sp.
order Hemiptera, Anthocoridae,
and others, many species
Rattus sp.
family Staphylinidae, many species
family Coccidae, many species
Drepanaphis acerifolii
Tetranychus urticae
Protoparce quinquemaculata
family Vespidae, many species
family Aleyrodidae, many species
7, 27, 35
7, 9
7, 9
14, 24
7
14, 15, 22
22
5, 10, 11, 12, 13
16, 17, 20, 21,
22, 26, 27, 35
17
7, 9, 10, 22, 25
19, 22, 30, 31
7, 9, 18
24
14
14, 15
4, 5
27, 28
14, 20, 22, 24,
26, 27
-38-
------- |