INSECTS THAT MIGHT EAT YOUR
VEGETABLES from THE GARDEN SPOT
First, before entering this chamber, you must take the following pledge:
You don't have to believe those things but you should know that I do and that I have been gardening successfully since 1972 using the above as my guide. There have been times when I have lost corps to insects and I have not always been able to figure out why or to find a solution that I like. I am currently having problems with flea beetles on broccoli and radishes and I have had a problem with my spinach for the past 4 years that I have not been able to solve. If you are looking to me as someone who has all the answers, you need to look further. I just love gardening and one of the reasons I love it is that it is always different, always presenting new mysteries to be solved, and, for however many years ago 1972 is, always putting wonderful food on the table.
First, an attitude check. Don't think of the garden spot as a place where a wide variety of animals, miniscules and vegetables are lying in wait to attack the plants you want to grow. The vast majority of critters are beneficial. I enjoy arguing that everything I encounter in gardening is beneficial including mosquitoes. It is important to remember this lest you be tempted to spray something to kill an insect or bacteria that may be doing some damage to your crop. If you use a poison that kills on contact, you are killing hundreds of thousands of beneficial insects and microscopic organisms for every one of the critters you have identified as a problem.
Identification is the first step in any sensible method of pest control in the garden. The easiest and surest identification is to catch the pest in the act, to see it doing whatever it is doing that you don't want it to do.
Animals can be identified by footprints, scat (I don't know why naturalists call wild animal manure scat.) sometimes scent, fur, and their habits. Insects are most often identified by what they are eating as most have favorite foods and do not eat indiscriminately. Some insects are very hard to see either because of camouflage, because of their size, or because they don't wait around to be seen. Some of them generate "scat" that can be helpful in identifying them. Others can be identified by the part of the plant they are eating or the way they eat.
Remember, healthy plants do not attract insect "pests." Think of insects that damage crops as indicators that a plant is not healthy rather than as pests. Their job is to clear away poor quality living things so that general health will prevail. If you want to understand why I believe this so strongly, read the piece on aphids.
The articles below are from my experiences. If I think you may want to try an approach that I have not used, I'll put a note that "the book says." There are several books that I have found helpful. My old favorite is The Gardener's Bug Book by Cynthia Westcott. It is not organic but it is the best identification source. I also have a couple of newer books from Rodale Press: The Organic Gardener's Handbook of Natural Insect and Disease Control and Controlling Pests and Diseases. The key to a good identification book is that it will lead you to the predator through the plant. You can identify the plant by name and that should be the key to finding the insect.
Not that naming insects in the garden is all that difficult. When you see a small black beetle jumping off your plants when you approach you might be tempted to call it a flea beetle. You would be right. A green worm eating the cabbage? Cabbage worm, of course. A green worm that loops when it moves like an inch worm and that is eating your cabbage? A cabbage looper wins the prize. But the cabbage worm and cabbage looper can also be found on broccoli and other members of the family and when on broccoli it is not called the broccoli worm. And how would you know that the brick-red grub doing a job on the potato leaves is the Colorado potato beetle?
Entering this portal is frequently done by people who are distressed at some damage being done to a crop they have planted and are nurturing. I have been there (see Cabbage worms). My first advice to you is, "Don't panic." If the culprit is another mammal, you do need to act rapidly but If the damage being done is by insect or disease, first, it will not spread to everything in the garden and second it will probably not even wipe out the crop it is currently damaging.
Much of the information on insects originally appeared in MOTHER EARTH NEWS in early 1997. It was one of the earlier articles I wrote for them. I am a regular contributor. My most recent is on genetic engineering, a really scary topic. It will be on newsstands late in 1999--perhaps in time for Halloween.
One of my favorite examples of healthy plants not attracting insect pests happened in my second garden. I planted four rows of turnips. Don't ask me why I planted so many turnips. It was just one of those things. I guess there were enough seeds in the packet. Whatever. The plants were looking beautiful until one day when I noticed some of them were wilting. I looked more closely and found the stems of the plants were covered with black aphids. They were infested. I couldn't believe it. Since I didn't know what to do and since I didn't think I would miss the turnips anyway, I did nothing.
The result was a mystery that puzzled me for several years. The aphids did not destroy all the plants. They got the plants they were covering but as the attacked plants got weaker and weaker I noticed that the plants at the ends of the rows were fine. Here were four 25 foot rows of turnips in which the center section of all four rows had been basically annihilated while about four feet on either end of the rows were left virtually untouched.
It was three years later when I was working on illustrations for my book that I came upon an explanation to the mystery that suits me. The illustrations were garden plots for each year drawn to scale and placed on the paper in the same relationship one year to another. I found that the turnip rows of the second garden crossed the corn patch of the first garden. The aphids had destroyed the turnips that were growing in soil that had hosted corn the year before. Rows of other vegetables crossed the corn patch without incident. The turnips did fine in ground previously inhabited by beans, beets, lettuce and potatoes. My non-scientific conclusion was that the corn took something from the soil that I did not replace and that the turnips needed.
There have been scientific studies conducted that support the claim that insects attack plants that are not receiving a proper balance of nutrients. There have also been more examples in my garden over the years. The principal things that I do to protect my crops from insects is to rotate the crops, maintain a high level of humus by adding some bulk organic material every year and changing the bulk material every so often (horse manure with shavings, chicken manure or seaweed, hay, leaves, etc.) A soil test every other year or so also helps keep me on track.
The probable reason I did nothing about aphids was that I realized I had planted too many turnips, especially since they are not a favorite vegetable of mine. In subsequent years I have found aphids on nasturtiums. The irony is that the nasturtiums were planted to repel aphids. I won't mention any of the books that recommend that but I came to the conclusion that nasturtiums would be better listed as a catch crop for the aphids. Planting crops for the purpose of repelling or attracting insects is called companion planting. Nasturtiums, marigolds and aromatic plants are generally mentioned in this regard. Frankly, I am not a great fan of companion planting. It doesn't do any harm and it may do some good but when you see nasturtiums or marigolds in my vegetable garden it is because they are pretty - kind of nice to have around.
What do I do about aphids? I haven't noticed any in my garden since 1974. For some this is just one of those mysteries of organic agriculture. Clearly aphids can destroy crops in Maine, more specifically, in my garden. Yet they were only here in my second and third garden.
What I recommend for anyone who has a problem with aphids is an immediate soil test. Get humus in the soil. Get the soil nutrients balanced. Use this indication of a soil problem to improve the health of the garden for next year.
If you want to try to rescue the current crop (the books say) knock the aphids off with a strong spray of water frequently. They will get tired climbing back on. Or use an insecticdal soap.
There is no soil too cold for asparagus as 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 beetleasparagus beetle and spotted asparagus beetle. They are both slender beetles about 1/4inch long and they both 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 these 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 was selling 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.
Cabbage worms and cabbage loopers
The first insect to cause me to panic was the cabbage worm or cabbage looper. These are two different insects but the difference is of no value other than to make a gardener who knows the difference feel superior to gardeners who don't. At the time of my first encounter I didn't know the difference.
I should back up a bit. I did not grow cabbage or any members of the cabbage family in my first garden. Potatoes, corn, onions, cucumbers, zucchini, tomatoes, green beans, peas, spinach, beets, lettuce and radishes all flourished without any insect damage. The reason, of course, was my purity. Perhaps luck in starting on fertile soil and in a place where no garden crops had been for several years had something to do with it, too. But when you are young and pure and self-righteous...well. I'm afraid I did not hide my light under a bushel basket that winter. Several more experienced growers with whom I came in contact asked what I had done about cabbage worms. When they found that I hadn't grown any of the crops that attract this green fellow they just gave me a superior smile.
I was sure my methods would work for any crop. Cabbage, cauliflower and broccoli were planned for the next garden. One of the controls you may come across when reading about pest control is separating crops of the same family. Insects that feed on one member of the family, say potatoes, may also feed on other members of the same family, tomatoes or eggplant for example. The idea is to make it difficult for insects to crawl from one crop to another. I have observed a lot of insects and, with the possible exception of the tomato horn worm, I have never been able to detect insects moving from one plant to another. My insects stay with the host upon which they were hatched.
Nor have I seen anything that would lead me to believe that a larger patch of one family is more likely to attract insects in flight than an individual plant. Flying insects get around and investigate just about everything that might be of interest to them. Do you think you are more likely to be bitten by a mosquito when you are in a crowd than when you are alone?
I planted these three brassicas (members of the cabbage family) next to each other. I planted them next to the central garden path and close to the house where I could keep an eye on them. And, lo, it came to pass that dark green balls similar in size and color to capers appeared in the center of the cabbage plants just as they started to form heads. Upon close inspection worms were discovered and they were eating the leaves of my cabbage plant. In panic I rushed to the Agway store for some Rotenone. Rotenone is a poison that is derived from plants. It does not hang around in the soil long and therefore poses no problem through accumulation. It is, however, a contact poison. It kills most insects with which it comes in contact.
My trip to buy this poison sobered me somewhat. By the time I got home I had decided to use it on only half of the plants. I would leave the rest for observation. Once in the garden with the Rotenone I decided to dust only a third of the plants. I ended up dusting a fourth of them. I hated it. I wasn't wearing breathing apparatus or protective clothing as should be done. I got a taste in the back of my mouth that was like sucking on pennies. Not pleasant. After the deed I changed my clothes and showered and still felt contaminated. That was the first and last time I ever used a poison in my garden. Natural or not, acceptable by organic standards or not, it is not for me.
This decision was not made entirely on my dislike of the poison and my role. If Rotenone were the only way I could grow cabbage and get it to harvestable stage, I would probably use it. At harvest that first year I harvested all of the cabbage I had planted. Three fourths of them had been left mostly to their own devices. I may have hand picked a few worms. Who could resist? If I can get cabbage that pleases me without using poisons, why use poisons?
The cabbage looper, for those of you who want to feel superior, has legs front and back and loops into an omega shape when it travels. The cabbage worm has legs all along its body and moves flat against the leaves. Just to confuse you they are both caterpillars.
"The cabbage looper, Trichoplusia ni. A native caterpillar common throughout the country. It attacks all members of the cabbage family - broccoli, Brussels sprouts, cabbage, cauliflower, collards, horseradish, kale, kohlrabi, mustard, radish, turnip - and also feeds on beet, celery, lettuce, parsley, pea, potato, spinach, tomato - and on flowers - carnation, chrysanthemum, mignonette, geranium, and others. The looper is said to be a serious lettuce pest. It winters as a green to brown pupa wrapped in a cocoon attached by one side to a plant leaf, and transforms in spring into a moth with mottled brownish fore wings, with a small silvery spot in the middle, and paler brown hind wings; wing expanse is just under 1 1/2 inches." That is from The Gardener's Bug Book by Cynthia Westcott. It goes on to give more information about the insects and some methods of control. I have several insect identification books but this is my favorite. Her chemical control methods are of no use to me but she does include natural methods when they make sense to her. Control that I like is usually based on knowing the insect well and she gives me the information I need.
As for the cabbage caterpillars I usually just pick them off if I feel like it or let them eat. Picking them from cabbage is difficult because they are hard to see. When the sun is low in the sky you can sometimes see them better using the sun to "X-ray" the leaves. In spite of the wonderful list of vegetables Cynthia says they will "attack", and in spite of the fact that I grow most of those, and in spite of the fact that I may see a dozen cabbage moths fluttering over the garden on a given day, and in spite of the fact that the females lay several hundred eggs each; these caterpillars have never been a problem on any vegetable in my garden. Go figure.
When I was selling vegetables it was more important that they look good if not perfect. The holes in the leaves of the cabbage plants and the worms in the broccoli can be eliminated with a very benign spray called Bacillus thuringiensis (Bt). This is a bacteria that is only harmful to Lepidoptera - butterflies and moths. Further, it has to be ingested by the larval - caterpillar - stage of the insect. It will not kill anything on contact. If you spray Bt on the leaves of plants you want to protect, it will only kill the Lepidoptera larva that eat those leaves.
Colorado potato beetles
There is one beetle in my garden that is difficult to ignore. The Colorado potato beetle is hard-shelled, very broad (3/8 by ¼ inch), very convex, yellow with 10 longitudinal black lines.
An example of a native insect which 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 will 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 it I could show her what a potato beetle looked like. It was perhaps my best year for potatoes. The rows were at their peak of growth and though I had not done anything 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.
When she had gone I went back to the potatoes and checked more plants. Sure enough the rest of the plants 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 two hundred-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. As such 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 husbandmanship of the soil. Perhaps mulching with leaves would be the secret. Perhaps planting in new soil. Perhaps rotating after corn, a grass. Perhaps planting next to beans, a companion crop. My quest continues. Being 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 also. 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 overwintered 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 4 to 7 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, about the size of a pin head, brick-red grub emerges and heads for the top of the plant where the most tender leaves are emerging. Not all of them make it to the top. Some will start eating 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 where you once could crush them all with one pinch you now have a dozen or more individual bugs to crush in a variety of 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 which is 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 egg clusters crushed as who could count them. They could pick the grubs and we could weigh or count them but that seemed like a bore plus it took away the incentive for getting 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 never presented 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. Along 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.Corn borers and corn earworms
These folks can be killed with Bt if you can get them to eat it. The corn borer and earworm don't hang out on the surface of the plants. The borer bores a hole in the stem and goes inside to eat. The earworm generally gets inside the ear and eats the kernels.
Before I tell you what I do to avoid these problems let me tell you what I would do if I had them. There are a number of good books dealing with garden insects. In them you will find a variety of ways to control insects. What any individual gardener uses is probably more a matter of preference and what seems to work best for them. Keep in mind that you won't always know that your method of control is effective in a given year. It is like the common cold. You can take aspirin, vitamin C, lots of water and get plenty of rest and the cold will leave in seven days or you can do nothing and wait it out in which case it will be gone in about a week. If you feel proactive measures need to be taken, you might consider doing nothing on part of the patch as I did with the cabbage.
Corn borers can be hand picked. You need to be observant. When you detect a hole in a corn stalk and perhaps some sawdust outside, cut a slit below the hole and dig out the worm. European corn earworms can be controlled by squirting mineral oil on the silk where it emerges from the ear.
Those are the measures I would take if I were going to do something. If every year were like last year in the corn patch, I might consider those actions. Last year I had corn earworm damage in just about every ear. I don't consider that a problem as the part of the ear they damage can be cut out leaving plenty to eat. But to go from virtually no damage year after year to a year like last is disconcerting. What happened?
Unfortunately a lot of things happened which is often the case in gardening. That's why it may take years of observation and some experimentation to figure things out. First, we had a winter that was unusually kind to life in the soil. We got snow cover early and it stayed on the ground insulating it all winter. The frost, which can go four feet deep some winters, was only an inch deep in my garden. Earworms and borers are usually killed in winters north of New Jersey and fly in to our fields and gardens from the south. It is reasonable to think many survived last winter. Second, there was a tropical storm that pumped lots of warm air into Maine from the south at just the right time to blow the moths of these caterpillars in our direction. Third, I transplanted corn for the first time ever to try to get an earlier crop. Fourth, I didn't fertilize my corn the way I usually do.
As you might guess, I don't like the first two possibilities. They indicate that my pest free corn in other years is just the luck of location. However, other gardeners and farmers in the area in other years have to spray or take other measures to protect their corn which helps me keep faith in my methods.
When I harvested the transplanted corn and found the earworm damage I was convinced it was because the plants had been weakened by transplanting. I was anxious to have this confirmed by the later plantings of corn. You can imagine my disappointment at finding all the plantings damaged by caterpillars. That leads to the fourth anomaly. I like to plant double rows of corn about six inches apart with 3 1/2 feet between. I start by hoeing a trench eight inches or so deep. I spread manure in the bottom of the trench, even a hot, raw manure like chicken. I then partially cover the manure by hoeing another trench three inches deep on one side of the manure trench. Seeds are planted in this trench, a pair every foot. This is repeated on the other side of the manure trench, the seeds covered, and, walla, insect control in the corn has been taken care of for another year. Last year the manure I used was two-year-old horse manure that had been stored outside. It was lovely humus but it didn't have much nitrogen which corn needs in abundance. That is what I am blaming my corn insect problem on. Hey, even if I had that much of a problem every year, it was still minor. As proud as I am of harvesting insect free corn year after year, I can still live with a little damage and less pride.
[The "last year" was three years ago. We have had unusually warm winters and unusually hot summers with hot humid air being pumped in from the south. My average of one ear in a dozen damaged by earworms has been holding. I don't know hat climate change is doing in other's gardens but, knock on wood, all it is doing for me is extending my season so far.
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 that 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 growing 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 stripped and spotted varieties. The spotted is greenish-yellow with black spots. The stripped, the one with which I am most familiar, 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 wormlike 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 twenty five 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 anythingvirtually no growth. I planted another hill leaving the first for observation. Ultimately this plant grew enough to have some flowers and some cucumbers but its output was not worth the effort of tending the hill.
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 is really 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 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 a foot in diameter a two 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 can be thus protected until they get their first true leaves. At this point they should be strong enough and the weather warm enough that they can outgrow 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 that my plants are so healthy 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 " That is as close a description of the land around my garden as I could give. It is actually a description from The Gardener's Bug Book of the winter habitat for stripped cucumber beetles.
I see cucumber beetles in the garden all summer long. They don't eat much. I hand pick 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 with spreading bacterial wilt and cucumber mosaic. My cucumbers and squash sometimes 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. My motto is "Ignore it. Maybe it didn't happen."
These are gray grubs that live just below the surface of the soil. Unfortunately their method of eating is to wrap themselves around the stem of a plant and cut through the stem. Damage is most often distressing when they cut off seedlings that you just bought and transplanted.
Cutworms are most frequently controlled by putting a collar around each plant when transplanting. Since the grub curls around the stem when it is cutting it a toothpick or other small stick pushed into the ground next to the stem may also work.
I think I read that somewhere but since I can't find it in any of my books right now, perhaps I dreamed that cutworms like wilting plants. No matter whether or not it is a proven theory. My experience over the years has supported that theory. I can only recall one time when cutworms bothered any vegetables other than those that had been transplanted. We had a very dry spring that year. I had not built up the humus level very much at that time and plants wilted in the draught. Cutworms damaged several crops that had been planted from seed. I had never seen anything like it before nor have I since. The damage seemed significant in the spring but as the garden matured what once seemed like big spaces filled in.
I protect my seedlings from cutworms by making their transition from seedling flat to garden as easy and stress free as possible. First the seedlings are hardened off by moving them outside in the flats for an hour or two the first day and increasing the time until, in a week, they stay out around the clock. Second, I separate the seedling roots from each other while sloshing them around in a bucket of water and working the planting medium back and fourth gently. This minimizes the amount of root damage. I put a tablespoon or so of liquid seaweed in the bucket of water just for good measure. When the transplants go in the ground the soil is firmed around the roots and then the ground is soaked so that the water will further put roots in contact with soil. Just in case, I hold onto extra plants either healed in at the end of the row or still in flats as replacements. It is seldom that I need a replacement.
There is another insect that may be found in corn. This poor fellow suffers the slings and arrows of gardeners though he and she are more beneficial than destructive. I refer to earwigs. The earwig did not get its name from being discovered in corn ears though that is a frequent day-time hangout. It was once believed that earwigs crawled into the ears of sleeping persons. A nasty thought especially since they frequently do get into houses. They are not particularly attractive either. They are brown, beetle-like insects, almost an inch long, with menacing-looking pincers at the tail end that look like forceps.
Earwigs eat a little bit of everything. When they eat decaying matter and other insects they are helpful to us. If they eat corn silk, it will cause the corn ears to be deformed. Did you realize that every kernel of corn is attached to a strand of silk. If the strand is damaged, that kernel will not develop. I have never noticed much damage from earwigs so I leave them alone. Anyone who wants to get rid of them can take heart in the knowledge that they don't fly worth a darn. Most earwig movement is as hitch-hikers. You may bring some home from the florist or the grocery store.
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 hand pick them so you can rule that out as a control.
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 generally 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 germinate 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 usually warm weather returns in time for the plants to put on vigorous growth that quickly overwhelms the damage.
There are only three plants that suffer significantly from flea beetlesradishes, 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 over night 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. Being 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 the garden soil. Also, the garden soil can pull moisture from below which the flat can't. I rationalize that the extra effort of watering is balanced by it being easier to transplant from a flat 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 they get plenty of water; the transplants will start growing vigorously enough for new growth to well outpace the flea beetle's feeding.
Interestingly flea beetles are around all summer going through a couple of generations in our climate yet I am only aware of them in the spring. Another interesting things 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 since beetles do most of their growing in the larval stage. Once it becomes a beetle it is fully grown. Flea beetles are 1/10 of an 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 loosing the battle against flea beetles, you can literally shoo them away and cover the plants with 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 the cucumbers and squash. I think flea beetles are most often an indicator that I am trying to grow a plant in soil that is too cold for it.
Leaf miners are the larval stage of a fly. They hatch out of eggs laid on the underside 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 it had done its damage. 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.
Destroy the leaves that contain the miners or just crust the maggots. If the problem is sever, try to figure out what is causing the plant to be under stress--nutrient imbalance in the soil, unusually weather, killer smog, whatever. Just put yourself in your plant's place.
Mexican Bean Beetles
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 county 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 lady bug. It is a metallic yellow to tan with eight black spots on each wing. As with 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 clusters and the grubs can be hand picked or crushed. Both are found on the undersides of the leaves.
Since I don't feel I have had any meaningful relations with this bug I will make no pronouncements. Maybe my bean plants are healthy. Maybe I am geographically blessed.
There are no sprays for this bug that will not kill more innocent insects than guilty. Some reference books say that there are resistant varieties. I read all the descriptions of beans in three catalogues and found no mention of bean beetle resistance. Organic Plant Protection edited by Roger B. Yepsen, Jr. (Rodale Press, Inc., Emmaus, PA 18049) 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. The Rodale 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 in our tests. In other words if we are going to spray garlic juice we should only spray it on half the plants. If it seems to do some good, we need to test it again in another year, again with a control.
Root maggots are the larva of a fly. 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 rutabaga; you will see the damage when you 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 this as an indication that the plants are under stress.
Root maggots are very small and white. If you were looking for a hard, brown worm that got into some of your root crops, you are probably looking for wire worm. I don't have that listed elsewhere because it is really not a problem. You have probably started a new garden where there was sod before. The wire worm will disappear in a year or two.
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."
That dialogue took place after I had been gardening about 5 years. I'm not quite as smug now. Back then I didn't even know what he was talking about. Now I do see an occasional root maggot in my radishes. Turnips and rutabagas actually collect even more but they are bigger bulbs and the damage is really minimal. I don't do anything to control them but if I felt it necessary, I would probably use a row cover.
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 underside 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 7 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 might have a wilt of some kind it has been squash bugs.
Tomato Horn Worms
The tomato horn worm is a worm about the size of a finger. It is so named because of a horn on its back end. It is usually first noticed by the damage to the tomato plants. Where a day before there was a branch of leaves there is now a skeleton of stems. They will also eat green tomatoes. They are big and they eat a lot. I have never found a small one or their eggs. They blend in so well on the plants that I usually have to take a fair amount of time spotting them. One of the clue that helps me most is the dark green balls of excrement. I'll spot these and then look around above the evidence.
I hand pick them. The horn can be scary even for an old bug-picker like myself. When you pull the worm off it whips around causing you to think you might be hurt. Not so, but still you might want to wear gloves or use pliers or something to do them in without grasping them with bare fingers. I'm generally too lazy to get gloves or pliers so I just steel myself for the task.
Bt (see cabbage worm) also works as a fine spray. Frankly, it is more work to get out the spray than to just seek out the culprit. I've got the spray in my refrigerator and seldom use it. The last time I used it on tomatoes was a year when I was very busy and had a lot of tomatoes growing. I would start trying to find them and then time would run out so I sprayed.
The moth of the tomato horn worm can be mistaken for a hummingbird. It is that big and it acts like a hummingbird too.
© 1998, Mort Mather
Mort is a husband and father. He authored a book, Gardening For Independence and was named Environmentalist of the Year by Down East Magazine in 1987. You can eat his organic produce at his son's southern Maine restaurant. His address is 802 Bald Hill Road, Wells, ME 04090.
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