Healthy Gardens and Low-Maintenance Pest Control

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ILLUSTRATION: MARY JO KOCH
Flea Beetle.

Learn how Mort Mather combats beetles and explains how healthy gardens and low-maintenance pest control can keep your garden produce protected. (See the beetle illustrations in the image gallery.)

In my last article I covered eight of the 17 insects that
have made themselves known to me by damaging crops in my
garden. Though this is the second in a two-part series, I
must go over the philosophy and some basic facts that I
believe should guide every gardener who wants healthy gardens and low-maintenance pest control. Without this, a
discussion of insects has the potential for becoming a
handbook for war, “There are bugs in my garden! They must
be eating my babies! Kill! Kill! Kill!”

In 25 consecutive gardens in the same spot I can’t recall
ever having a crop completely wiped out. Sure, I got a lot
less turnips than I planted one year, but I had planted too
many anyway. We never would have eaten the crop that 100
feet of turnips would have yielded. The aphids did me a
favor by cutting the harvest down to something much more
reasonable.

I ran out of potatoes in January this year. In a good year
I have enough potatoes left in the spring for the next
planting. It was rodents rather than insects that damaged
that crop, and I do need to figure out a way to deal with
them. I’m currently trying to befriend a homeless cat that
has been hanging around the house. I hope by providing it
milk it will provide some mouse and mole control. But back
to insects.

Public Enemy No . . . 1.7%?

I want to do everything possible to get people to think
positively about insects. The vast majority of them are, at
worst, benign. Consider this quote from my favorite insect
reference book:

No one knows exactly how many kinds of insects there are,
and figures vary widely even on the number already
described. The fourth edition of Destructive and Useful
Insects
(Metcalf, Flint, and Metcalf, 1962) gives
686,000 as the estimated number of described living species
of true insects with perhaps 100,000 of these in North
America. A Field Guide to the Insects (Borror and
White, 1970) gives 88,600 as the number of species in North
America north of Mexico and estimates that perhaps 1,000
insects may be found in any fair-size backyard.

Relatively few insects-probably not more than a tenth of
the total number–can be designated as public enemies.
The rest are either harmless or decidedly beneficial.
Without insects, life as we know it today would not exist.
We depend on insects for pollination of 85 percent of our
fruit and many of our vegetables. They play a large role as
scavengers. They provide food for birds and fish. They give
us honey and wax, shellac, cochineal, and silk, and they
have a minor role in surgery and medicine. Practically
every insect order contains some useful species that live
on destructive insects.

It is only within the last 30 years, when some chemicals
have reached such a high degree of non-selective efficiency,
that we have learned the extent of the role played by
parasites and predators in reducing harmful insects and
mites. (See The Gardener’s Bug Book, Fourth
Edition, by Cynthia Westcott, Doubleday & Co, Inc.,
1973).

If there are roughly 1,000 different insect species in the
neighborhood of my garden, and only 17 of them have
attracted my attention by eating my vegetables, then the
percentage of potential problem insects is 1.7. To focus
the majority of the attention on these few insects is a
distortion of the real world. It is a gross
misrepresentation. It is like being afraid of going to a
city because all you ever hear about is all of the bad
things that happen to people.

I actually look upon that small percentage of species of
insects that eat garden plants as the most important. After
all, they care about the same thing I do. What possible
good could a mosquito be to a garden? Mosquitoes don’t care
about plants. The number of mosquitoes in my garden tells
me nothing about the health of the garden. And it would
take a tremendous number of them to add anything to the
soil. Their greatest value may be in telling me when it is
time to leave the garden in the evening.

Aphids, on the other hand, send me an important message.
When there is an aphid infestation on a row of plants, I
know that the plants are under stress. The aphids are not
causing the stress. They are indicating that there is
stress, something they can sense that I can’t. The plants
look fine to me.

Consider another indicator-the oil light in a car. When
this warning light comes on, you know that there is a
problem that must be attended to right away. You pull into
a garage and tell them the oil light is on. They reach
behind the dash and pull out a little light bulb. Showing
it to you they say, “There, this won’t come on again:’ And
you are on your way, right? Yeah, right, but not for very
long because, of course, the bulb was not the problem. It
was indicating a problem in the engine, a problem that if
not fixed soon, will develop into a larger problem.

We should look upon insects that eat our vegetables as
indicators of a larger problem. The problem might be that
we planted a particular crop too early, and it is
struggling in soil that is too cool for it to grow
vigorously. Or the trouble may be too much or too little
water. But it is usually an imbalance in soil nutrients,
either too little or too much of one of the 17 elements
necessary for the healthy growth of most plants.

In my previous article I dealt mostly with
Lepidoptera. These butterflies and moths lay eggs
on plants, that hatch into caterpillars. The caterpillars
eat until maturity, are transformed into a pupa, and then
molt to become a winged insect again.

Most of this article will be about beetles. Beetles also
fly and lay eggs. The eggs hatch into grubs, and it is in
this phase that they gain the most weight. However, adult
beetles also eat and are sometimes a greater problem than
the grubs. The Japanese beetle probably springs to mind for
many. I remember handpicking Japanese beetles from our
grape arbor in New Jersey when I was growing up. While I
have seen a few in my garden from time to time, they are
not much of a problem in Maine. I have seen traps out for
them, so I guess they are bothering some people.

I’ll start with the smallest: flea beetles. I wasn’t sure
how that should be spelled at first. They are hardly bigger
than a flea but when you approach them, they flee. This
quick movement makes it impossible to handpick them, so you
can rule that out as a control method.

I have observed damage from flea beetles on baby plants and
transplanted seedlings of tomato, pepper, eggplant, potato,
radish, broccoli, cabbage, cauliflower, kale, cucumber, and
squash. They make small holes in the leaves. In the case of
transplants like tomatoes, peppers and eggplant, I often
feel they are doing me a favor by cutting back the leaf
mass to help put it in balance with the roots that were
damaged during the ordeal of transplanting. The damage to
the young cucumber and squash plants is minimal. It
probably only occurs when the seeds germinate early and the
warm weather that allowed them to do so is followed by cold
weather that causes the plants to grow very slowly, if at
all. If slow growth continues for too long, the beetles
will severely damage the plant, but warm weather usually
returns in time to promote vigorous growth that quickly
overwhelms the damage.

There are only three plants that suffer significantly from
flea beetles-radishes, broccoli, and cauliflower. The
radishes always make it in the end, but the first couple of
plantings attract so many flea beetles that I usually
expect them not to survive. Broccoli and cauliflower
directly seeded in the garden have had their baby leaves
completely eaten. At least I think it was flea beetles. One
day I had a foot-long row of inch-high seedlings with flea
beetles poking holes in the tender leaves. The next day
there were just stems. It could be that something else came
along in the night, or it could be that I ignored the
plants for more than overnight, but damage to these
seedlings by flea beetles has been enough in successive
years for me to change my practices. Flea beetles like this
crop a lot, and the best way for me to get broccoli and
cauliflower is to start the seedling in flats.

The frustrating thing is that I used to plant short rows,
just a foot for each, and then transplant from these short
rows.

As a lazy gardener, I try to plant in the garden whenever
possible and let nature take care of water, light, and
nutrients. The flea beetles made it necessary for me to
replant, which was more work. I could cover the seedbed with
gauze, but that was another thing to worry about. I finally
reached the conclusion that the easiest way to get broccoli
and cabbage seedlings started was to grow them in a small
flat. I do have to water it even if I leave it outside,
because the soil in a flat dries out much faster than garden
soil. Also, the garden soil can pull moisture from below, but
the flat can’t. I rationalize that the extra effort of
watering is balanced by the easier task of transplanting from
a flat rather than from a garden seedbed.

The flea beetles go after the transplants, of course. The
trick is to make the transition easy enough so the plants
have a minimal setback. By taking care that the roots are
not severely damaged, that the soil is in good contact with
the roots, and that the plants get plenty of water, the
transplants will start growing vigorously enough to outpace
the flea beetle’s feeding.

Interestingly, flea beetles are around all summer and go
through a couple of generations in our climate, yet I am
only aware of them in the spring. Another fascinating thing
is that I have never been aware of their larval stage.
Since their larval stage in not mentioned in any of my
reference books, I guess it isn’t important, but it is
still interesting because beetles do most of their growing
in the larval stage. Once it becomes a beetle, it is fully
grown. Flea beetles are 1/10-inch long, and their eggs are
minuscule. It is going to take a lot of them to make a big
difference.

If you have some plants that appear to be losing the battle
against flea beetles, you can literally shoo them away and
use gauze or an agricultural row cover. The row cover has
the added advantage of warming the soil, which will
probably help the plants grow more vigorously. I have done
this with cucumbers and squash. I think flea beetles are
most often an indicator that I am trying to grow a plant in
soil too cold for it.

There is no soil too cold for asparagus, because it is a
perennial. The crowns send up shoots from a foot or so deep
in the ground when the temperature or the soil or some
cosmic signal tells it to. Since I exercise no control over
the growth of this plant, I take no credit or blame for
timing. There are two kinds of asparagus beetle: asparagus
beetle and spotted asparagus beetle. They are both slender
beetles, about 1/4-inch long, and have spots. The regular
asparagus beetle is black with yellow spots, and the
spotted one is orange with black spots. I don’t have
problems with either of them. Actually, they are kind of
attractive on the plants. There may be a few around while
I’m harvesting and may eat a little of the head of the
asparagus, causing it to be bent or look chewed up. That is
not good for market, but it doesn’t bother me. When I sold
asparagus I don’t recall ever having to hold out any to
make the bunches perfect.

The beetles come in greater numbers after I have stopped my
harvest and the plants are maturing into ferns. I suppose
the foliage they eat may decrease the plants’ ability to
store energy in the crown, which may decrease the crop the
next year. They have never completely defoliated a plant,
so I have not given them any concern.

Cucumber beetles have caused delays in my first cucumber of
the year. Some may think that because I have had to replant
broccoli or cucumbers I should call it a crop loss to
insects. There have been years when, if I had not
replanted, I would not have had broccoli or cucumbers. But
I did replant. The damage was done very early in the
season, so there was plenty of time to do the job again.
Being lazy, I would rather not have to do the job again.
Being competitive, I would rather have the crop come in as
early as possible. Being philosophical, I accept what is
and go on from there.

Cucumber beetles are about the same size and shape as
asparagus beetles. There are striped and spotted varieties.
The spotted is greenish yellow with black spots. The
striped, the one I am most familiar with, is yellow with
three black stripes. It starts flying in the spring before
the cucumbers or squash have sprouted. When their favorite
crop appears, they will do some eating of the leaves, but
this damage is minimal. What really hurts is if they lay
eggs on the ground under the plant or on the stem at ground
level. When the eggs hatch, the thin, white worm-like larvae
feed on the roots. Since this is hidden from view, it goes
unnoticed until it is too late to do much other than plant
again. In 25 years of gardening, I can only recall having
this problem once. I kept looking at the cucumber plants,
and they just weren’t doing much of
anything–virtually no growth. I planted another hill,
leaving the first for observation. Ultimately this plant
grew enough to have some flowers and cucumbers, but its
output was not worth the effort of tending it.

I usually let nature take its course, meaning that I plant
and observe what happens. There have been some years that I
have put gauze over the hills of cucumbers and squash. This
really is a pretty good idea for several reasons. It will
act as a barrier to cucumber beetles and flea beetles. It
will also warm the soil several degrees above the
temperature of uncovered soil, which helps these
warm-loving crops. Covering a hill is really about the
easiest plant protection I can think of. If the hill is I
foot in diameter, a 2-foot square of gauze will cover it.
The edges of the gauze can be covered with soil, or the
corners held down with stones. The plants will be protected
until they get their first true leaves. At this point, they
should be strong enough and the weather warm enough so that
the plants can out grow any damage from insects.

Now a little pride (I hope not arrogance) creeps in. Seldom
have I used this preventative measure and seldom have I had
a problem. If I use the gauze, I can’t prove my plants are
so healthy that they won’t attract cucumber beetles. As for
whether or not the beetles are in the vicinity consider
this: ” . . . woodlands near the vegetable garden, under leaves
or rotting logs, in lowland hedgerows, or near wild food
plants such as goldenrod and aster…” This is actually a
description from The Gardener’s Bug Book of the
winter habitat for stripped cucumber beetles. It is as
close a description of the land around my garden as I could
give.

I see cucumber beetles in the garden all summer long. They
don’t eat much. I handpick them if they are conveniently
located and I’m in the mood. They are somewhat cagey
though, and frequently fly at my approach. They are blamed
for spreading bacterial wilt and cucumber mosaic. My
cucumbers and squash occasionally get some late disease. I
haven’t bothered to figure out what it is because it comes
so late in the season that I really don’t care much. I’m
not even certain it is a disease, though it probably is. At
first I thought the plants had just reached maturity and
were dying of old age. I am obviously not a good one to
talk to about plant diseases, since my motto is “Ignore it.
Maybe it didn’t happen.”

There is one beetle in my garden that is difficult to
ignore. The Colorado potato beetle is hard-shelled, very
broad (3/8″ x 1/4 inches), very convex, and yellow with 10
longitudinal black lines. It is a perfect example of a
native insect that suddenly became dangerous to cultivated
plants. For many years this beetle lived on the sandbur
weed on high plateaus at the base of the Rocky Mountains.
It was described in 1824 and had probably been around as an
obscure beetle for a long time. But the pioneer settlers of
the West brought with them the potato, which the beetle
found much to its taste. In a short time this almost
unknown insect became, under the title of “potato bug,” the
best-known insect in America. It migrated eastward at the
rate of about 85 miles a year, following potato plantings,
appearing in Nebraska in 1859, Illinois in 1864, Ohio in
1869, reaching the Atlantic coast by 1874. Eventually it
made its way to Europe, where it is well established in
France, Holland, Belgium, Spain, parts of Italy, and in
other countries. It appeared in England but was eradicated
there. It is now a problem throughout the United States
except in parts of Florida, Nevada, and California.

The Colorado potato beetle humbles me. I have to admit
that it has come to my garden in numbers that can defoliate
plants. I have to admit that it comes in worrisome numbers
more often than not. But I have some experiences that support
my belief that healthy plants in a healthy soil do not
attract insect pests. One year a woman dropped by to ask if I
could show her what a potato beetle looks like. It was
perhaps my best year for potatoes. The rows were at their
peak of growth and though I had not done anything to
discourage them, there were no signs of potato beetles. I
looked down the rows and saw one plant that looked smaller
than the rest. I went to it, pulled back the leaves exposing
the undersides, and sure enough found three clusters of
beetle eggs to show my guest. Some more looking and I was
able to show her a couple of adult beetles.

After she left, I went back to the potatoes and checked
more plants. The rest were free of any egg clusters.

Another year I planted potatoes in the market garden, not
because I was planning to sell them, but because potatoes
are said to like new soil. One day, when the plants were
nearing full size, I pulled back several to check for egg
clusters. They seemed to be averaging about one cluster per
plant. I was too busy at the time to pick eggs from
200-foot rows and I never got back to them. To my amazement
I never saw any grubs or any damage to the plants. I can’t
imagine that I checked the only plants with egg clusters,
but if there were more, why didn’t they hatch?

Those two years were exceptions. It would seem more
reasonable to attribute the paucity of beetles to a
fluctuation in their population in the area, probably due to
the weather. I have concentrated on the soil for potatoes
many years, hoping that I would get it just right and there
would be an exceptional year that I could attribute to my
husbandry of the soil. Perhaps mulching with leaves would be
the secret. Perhaps planting in new soil. Perhaps rotating
alter corn, a grass. Perhaps planting next to beans, a
companion crop. My quest continues. As a Taurus, I don’t give
up easily.

In the meantime, how do I get a crop? Until recently there
was only one control that I found acceptable: handpicking.
This is an honorable practice and reasonable in a garden.
Before chemicals it was also the only practice for a
farmer. To control potato beetles by handpicking, you need
to know a little bit about them. First, the adults pop out
of the ground about the same time the plants do, if you are
planting as early as possible. Planting later is one way to
decrease their damage. The beetles that over wintered in or
near your garden may fly away in search of food if they
don’t find it to be handy.

The adults fly around looking for each other and for a good
place to lay eggs. They eat a little but not enough to be a
problem. They may be tasting plants to make sure they have
found a good one for their offspring. They lay eggs on the
underside of leaves of potato plants or other members of
the same family (eggplant, tomatoes, and deadly
nightshade). The egg clusters are bright yellow-orange and
a good size for crushing between thumb and forefinger. The
eggs hatch in four to seven days-very important. The
difference, as you might imagine, is caused by the air
temperature: Handpicking is best done before the eggs
hatch, which means that the plants should be checked once a
week in cool weather and every four days when it is hot and
humid and you don’t feel like doing it.

When the eggs hatch, a small brick-red grub (about the size
of a pinhead) emerges and heads for the top of the plant,
where the most tender leaves are emerging. Not all of the
bugs make it to the top. Some will eat pretty much where
they started. Others will end up heading out toward the
ends of leaves and stems other than the main one. The
result is that instead of crushing them all with one pinch,
you now have a dozen or more individual bugs to hunt down
in various locations. They go from pinhead size to the size
of adult beetles in about two weeks. To get to this size
requires a lot of eating–not particularly good for the
plants. The bigger the grubs get, the messier they are when
squeezed, as you might imagine.

I tried to entice my children into picking potato beetles.
I couldn’t very well pay them for the number of crushed egg
clusters-who could count them? The kids could pick the
grubs, and then we could weigh or count them, but that
seemed like a bore-plus, it took away the incentive for
removing the clusters before they got out of hand. Then I
hit upon the scheme of offering $50 to keep the plants free
of grubs. I would check every week and deduct a nickel for
each grub or cluster I found. And I would give them a
couple of hours notice before I checked. I guess I didn’t
present it properly because I never interested either Josh
or Caitlin in this enterprise. It was my plan from the
beginning to never turn my children off to gardening by
making it a place of unpleasantness, so I couldn’t force
them to do the job.

My own handpicking worked pretty well most years. I would
be fairly diligent when the timing was once a week. It
didn’t take too much effort to travel up and down the rows,
pulling the plants back to expose the undersides of the
leaves. The yellow-orange clusters are easy to spot and a
pinch crushes the eggs. Heat and humidity slow me down just
when the eggs start hatching faster. At about this time the
plants are in flower and growing so vigorously that I feel
they may be able to take care of themselves. There have
been some years when some plants were completely
defoliated. I have no doubt that the harvest has been
diminished because of the beetles. However, most years I
have harvested the three or four bushels we need to get
through the winter.

Two or three years ago a new strain of Bt (Bacillus
thuringiensis var. san diego) was
developed. This is a
bacterial disease that will kill Colorado potato beetle
larvae and nothing else. While I think the precautionary
advice on the label (that it be kept out of the reach of
children, that contact and inhalation be avoided and that
it be kept out of lakes, ponds, or streams) should be
followed, I feel much more comfortable using it than I
would any chemical insecticide. I find this insecticide
acceptable for use in my garden primarily because it does
not kill innocent insects. However, whenever I use it, I
recognize that I have not yet found the real problem. I am
pulling the warning light bulb rather than fixing the real
problem.

Cynthia Westcott says the Mexican bean beetle is “doubtless
the worst enemy of eastern home vegetable gardens.” It has
not been so for me, but I’m not going to take any credit
for this one. I haven’t heard other Maine gardeners talk
much about this relative of the lady beetle, so I suspect
that it just doesn’t like our weather very much. Like the
Colorado potato beetle, the Mexican bean beetle spread
across the country from Mexico. I have had it visit my
garden. There might be one or two hatches in the whole bean
patch. Only one year were there enough to merit my
attention.

The Mexican bean beetle is about the size of the potato
beetle and the shape of a ladybug. It is a metallic yellow
to tan with eight black spots on each wing. Like the potato
beetle, it is the grub that does the most damage. The grub
is yellow with what the books call spines. I call it fuzzy.
It eats from the bottom of the leaf and turns leaves into
lace. It will also eat the beans, which makes it even more
of a pest. Egg dusters and the grubs can be handpicked or
crushed. Both are found on the undersides of the leaves.

There are no sprays for this beetle that will not kill more
innocent insects than guilty ones. Some reference books say
that there are resistant varieties, though I have found
little evidence of such resistance. Organic Plant
Protection,
edited by Roger B. Yepsen, Jr. (Rodale
Press, Inc.), suggests a number of companion plants that
may keep the beetle away. One of those is potatoes, and I
always plant potatoes and beans next to each other. That
may have something to do with my lack of Mexican bean
beetles, but I doubt it. This book also mentions some
home-concocted sprays involving wormwood, garlic, mint,
matricaria, wild morning glory, and cedar. I think anything
is worth a try, but I am loath to pass on any home remedy
that has not been properly tested. That is not to say that
we have to get scientists involved. We have to be willing
to keep a control factor in our tests. In other words, if
we are going to spray garlic juice, we should only do so on
half the plants. If it seems to do some good, we need to
test it again in another year, again with a control.

That’s it for the beetles that have done damage in my
garden. Lest you are down on beetles, remember that the
best friend we have is a beetle. Ladybugs have a voracious
appetite for aphids and scale insects. Adult ladybugs will
eat about 50 aphids a day. In the larval stage they eat
about 25 aphids a day. A single larva has been known to
consume 90 adult and 3,000 larval-scale insects during its
lifetime. Don’t ask me who counted them.

I don’t think I would buy ladybugs unless I was trying to
repopulate an area where a lot of spraying had been done.
The problem with bringing them in from somewhere else is
that they may not have enough to eat, in which case they
will either fly away or die. Better to keep from
interrupting the natural balance in and around your garden.
If there are a lot of aphids in your garden one year, there
is a good chance that a ladybug will find out about it and
decide your garden is a good place to start a family.

The squash bug is the only true bug that calls attention to
itself in my garden. While we think of most insects as
bugs, entomologists are more selective. Their bugs have
some specific traits like front wings that are leathery and
back wings that are membranous. Bugs have a gradual
metamorphosis with the nymphs looking like adults without
wings.

The squash bug is shield-shaped, and if you have ever
squashed one you probably remember the smell. The eggs are
laid on the undersides of leaves and are hard to squash. I
usually get a hatch or two on my summer squash fairly late
in the season. By the time I see them, the nymphs are
usually nearing their last of the five molts they go
through before adulthood. There are usually a lot of them
in the same place often on the same leaf. I just clap the
leaf between my hands and squash most of them in one
impulsive move. The smell doesn’t bother me. If they were
more of a bother, I would probably look for the eggs, which
hatch in seven to 14 days.

Squash bugs probably get on my winter squash, but there
is such a tangle of vines and no need to get involved with
them on a regular basis that I don’t see them. They inject a
poison into plants they feed on, which causes leaves to turn
brown. It may be that some of the times I thought I had a
wilt of some kind, it was squash bugs.

Root maggots and leaf miners are both the larval stage of a
fly. Leaf miners hatch from eggs on the undersides of
leaves. The maggot gets in between the top and bottom
layers of the leaf and feeds there. Even if you wanted to
use a poison, it wouldn’t affect a leaf miner, at least not
until the damage was done. The damage shows up as mottled
leaves or light patches. I have had them in spinach, Swiss
chard, and beets, all of the same family, so it is probably
the same fly.

In the case of root maggots, the fly lays its eggs at the
base of the plant. When the egg hatches, the maggot digs
in, feeding on the root. If it is a root crop like
radishes, turnips, carrots, or rutabagas, you will see the
damage at harvest. Radishes are in the ground such a short
time, the maggot is likely still there in the radish. Root
maggots in the roots of cabbage may retard the growth of
the plant, or it may wilt and even die. In any of these
cases, if there is a lot of damage to root crops or if
other plants wilt, take it as an indication that the plants
are under stress.

I remember having a debate about organic methods with a
commercial vegetable grower. At one point he asked what I
did about root maggots on radishes. “I grow healthy plants
in a healthy soil. I don’t have root maggots.”

“My plants are healthy,” he retorted. “Dave,” a friend of
his piped in, “you don’t have any earthworms in your soil.”

“What’s that got to do with it?”

“That’s what he’s talking about. Healthy Soil has
earthworms.”