A Listing of Other Plant Pests: A-E
In people’s homes certain species of ants can be a problem, and this is well known. Carpenter ants — though not wood-eaters — do make galleries in structural wood and can make an otherwise usable house into an unsafe structure by weakening the wooden members. Many sugar-eating ants, including carpenter ants, can be nuisance pests as they forage in kitchens, bathrooms and other suitable rooms in their never-ending search for food. Moreover, they can spread harmful bacteria. This is also true of protein-eating ants, which may also bite you. And, speaking of biting, southern fire ants can be a real pain — literally.
Homopteran pests like aphids, whiteflies, mealybugs and soft-scale insects, all produce a sugary, liquid feces-commonly called honeydew-which many ants just love. They love it so much, in fact, that they’ll hang out with these pests, protecting them from many predacious and parasitic biocontrol agents. In this sense, ants can degrade the efficacy of a biocontrol program as ants may deny biocontrols access to their prey or hosts. These same ants will sometimes physically help in the spread of these pests as the plants they’re on begin to weaken, or as their demand for honeydew grows. There are chemicals which are effective for controlling ants, but being that you’re reading about the Green Methods, most of those chemicals are unsuitable. Boric acid baits are available as gels, pastes, powders and liquid feeding stations. They are the safest, most environmentally reasonable way of dealing with these pests — unless you can effectively bar their passage with barrier-type products such as diatomaceous earth or simple caulking. Boric acid baits are designed to take out the problem at its source as the bait is supposed to be brought back to the colony’s queen and brood.
If you grow apples, apple maggots will become a part of your life. Period. And spraying is how most apple growers cope with these pests. And this is understandable as apples are extremely difficult to grow using non-chemical means. It can be done, but if you try you’ll probably be running a cider- and apple by-product-heavy operation as good, unblemished picking apples will be fewer and further between and “drops” will be common. There’s nothing wrong with many of the apples which won’t pass muster, but try convincing consumers of this. Apple maggots are 6-8 millimeter flies with clear but patterned wings which lay their eggs in small punctures in the skin of apples. The flies’ eggs hatch and the resulting larvae tunnel their way through the meat of the fruit until the apples drop to the ground. The larvae then leave the fruit preferring the shelter of the ground to pupate. Conventional growers place a few red spheres — which are coated with a sticky substance — in their trees to capture the flies so they know when to spray. Organic and unconventional growers place many of these spheres in their trees in hopes of not only monitoring the situation, but to capture enough of these flies to reduce the over all population and, thus, the damage they cause. This is sound thinking. Additional controls include the use of repellent products such a garlic sprays, neem-based products (which can repel pests if applied heavily), apple maggot control bags, and Kaolin or China clay. Other techniques include removing and destroying, or utilizing, dropped fruits before the larvae exit the apples. Parasitic Nematodes are also a good control measure against the larvae as they dwell in the soil and exploit the pupae. Multiple applications would be necessary for the purposes of timing, but it is not critical as some of the pupae stay in the soil more than one season. Other potential tactics include planting cover crops around trees in hopes of sheltering ground beetles which may prey on them.
These are larvae of unremarkable-looking grayish-brown moths. The moths are about three centimeters and can be distinguished by a white dot on each wing-but that’s only if they are seen, which is unlikely for they are nocturnal. The worms or larvae are up to four centimeters long and striated with green, brown and whitish stripes running lengthwise along their plump bodies. The, worms, too, are nocturnal, and will probably not be seen chowing down on corn and other field and garden crops-and the damage will look like something was “chowing down.” Armyworms are found in forms varied from what we’ve described, and some show preferences to specific crops: beets, for example. A common characteristic, though, is their flair for feeding. Consumed parts may include leaves, stems, roots and tubers, and even the fruiting bodies themselves. Parasitic Nematodes can play a role in the control of these pests. They overwinter as larvae (or pupae, depending on species). Thus early to late spring or late summer to early fall may be a good time to attempt a nematode offensive. However, anytime armyworms are found as larvae in or near the soil will work. Bacillus thuringiensis (Bt) variety Kurstaki will also control these pests. When these worms bravely venture out at night to feed on upper plant portions, you’ll nail them with Bt-K. A last option would be to use a row cover to keep adults from laying eggs on the plants.
Moths! What a pain. These two centimeter long clear-winged black moths mate with wingless black females which lay their eggs on shrubs and trees in little “bags” made of leaves or pine needles. The larvae which hatch from the eggs venture forth, feeding as they go, eventually making new bags of their own in which to settle down and eventually complete metamorphosis. They grow to about two centimeters, enlarging the bags as needed along the way. Bacillus thuringiensis (Bt) variety Kurstaki can be used effectively against these pests if the larvae are targeted early in the season, before they become bagworms in the formal sense. As far as we know, the most effective method of ultimately controlling these pests is to get out there and physically remove the bags by cutting the silk which secures them to the twigs. (If the silk remains it can girdle a twig.) As another option, there are commercially available traps for capturing the flying male adults very late in the season. The traps used are pheromone or sex traps-they smell like girl bagworm moths.
Black Vine Weevils
These insects are major pests of many ornamental nursery crops. Some greenhouse crops fall victim to these pests, too-though this is atypical. Their feeding causes a distinctive notching of leaves when they are adults. As larvae, residing in the soil, they feed on roots. In either case they are not a welcome sight, even though they are seldom seem. Their feeding damage, however, isn’t likely to go unnoticed. Black vine weevils are fairly tough-looking robust insects approaching nine millimeters as adults and may be found during the day hiding out in sheltering debris, leaf litter, etc. In greenhouses they can sometimes be captured on sticky traps placed sticky-side-up on the ground. Better yet, though, for scouting, is to design harborages for them which can be quickly uncovered during the day. Parasitic Nematodes are a good method of controlling the larval and pupal stages of these insects. One university trial determined nematodes, when compared to the big-gun chemicals available, are one of the best controls for these pests.
You may think these inconspicuous fly-looking flies buzzing around your brassica or cole crops (cabbage-family plants) are not-a-problem, but think again. These little flies could be busy laying eggs in the soil at the bases of your plants in the spring and beyond. That is if they’re cabbage maggot flies. The eggs the flies lay hatch into white maggots which grow to seven millimeters-the same size in which they’ll be as adults. These larval maggots tunnel into the roots of the cabbage-family plants, where they can cause extensive physical damage and various root rots. Covering cole crops with a row cover will keep flies out of your plants. But a row cover might keep things too hot for these crops — they like it cooler. Moreover, if the flies’ pupae are in the soil already, the row cover will keep them in when they emerge in the spring. Parasitic Nematodes are an excellent option for the control of these pests. They’ll love those little maggots. A sheet made of black plastic or some other impenetrable and opaque material covering the ground around the plants works well to keep the flies laying eggs elsewhere. The plants will grow through slits in the plastic. It will also serve to keep the moisture in the soil. Other products may also help. Capsicum pepper wax or garlic products sprayed on the ground and lower plants portions may deter the flies.
wax or garlic products sprayed on the ground and lower plants portions may deter the flies. Carrot Beetles With many beetles it is the larval stage which is damaging to plants-especially when that damage occurs below ground-but with this species, it is the large red-brown beetles at fifteen millimeters adults which tunnels into the roots of carrot and other crops. The C-shaped larval grubs, which grow 25 mm., are in the soil, too, but tend to feed on grasses more than they feed on carrots. Parasitic Nematodes are a viable means of control, as long as your timing is right and you focus on a wide-ranging area around where your carrot crop is planted-including areas where there is grass or leafy debris.
Carrot Rust Flies
Another fan of carrots, these seven millimeter, slender redheaded flies can also be a problem. They lay their eggs in the soil near carrot plants. When they hatch the white larvae, the maggots that they are, feed on the carrot’s root hairs and the prized tap root. They cause physical damage and allow root rots to flourish. Row covers will protect carrot plants from egg-laying adult flies — assuming, that is, that they emerged from somewhere other than from under the row cover. Parasitic Nematodes will kill the larvae, so they are, once again, an option. Capsicum wax and garlic sprays may deter the adult flies.
Are carrots on the menu tonight or what? Here’s another bug which loves carrots. These six millimeter brown weevils do the same thing as the other carrot pests mentioned previously: they lay eggs, the immature stages eat. And the same controls will apply, too. Parasitic Nematodes, row covers, plastic sheeting, etc.
European, masked, rose and other chafers are pests many people are familiar with. Collectively, they are beetles of a particular family. And like most pestiferous beetles, they are damaging to plants in their adult and larval forms. Chafers feed on many different types of plants. The particular size and appearance of these beetles, and their subsequent diet, depends chiefly on which type of chafer you’re dealing with. The grubs or larvae are quite similar to the casual observer: they’re C-shaped whitish grubs. Their presence can also lead a mole invasion which, in its own right, can devastate a lawn or garden. (The best way to get rid of moles is to destroy their source of food: the grubs.) Like the other beetles, chafers are more readily controlled in their larval form as the adults are mostly vulnerable only to harsher chemicals. The adults can be picked off of plants by hand. Moreover, the plants can be protected by covering them with a floating row cover. But using Parasitic Nematodes will yield far better results. Additional control may be obtained from azadirachtin, the active ingredient in neem-based products.
The black and white narrow shield-shaped true bugs may be seen weaving their way through your lawn’s thatch. These bugs may be covered with a white powdery bloom and can grow to six millimeters in length. They attack certain grasses which lack endophytes and can cause yellow patches and areas of dieback. Probably making the most sense is to forgo susceptible grasses and to plant one containing endophytes. Your seedsman will know this information. “Endophytic,– may even be printed on the bag. This makes the most sense because other forms of control are generally too impractical.
Colorado Potato Beetles
These one centimeter and larger yellow and black striped beetles are widely known-especially in potato country (even though they are known to feed on other crops such as tomatoes). The adults and their orange larvae are big feeders and can cause tremendous damage in the form of ragged holes to complete defoliation. In some circles these beetles are considered major pests. Fortunately there are decent controls available. The most popular control are the Spinosad products.
As far as biological pest controls agents, some say ladybugs feed on the eggs of these beetles. On the other hand, spined soldier bugs, Podisus maculiventris, do prey on the larvae. And since they are now commercially available, are a biologically viable means of subduing these pests.
The larvae of these moths can be very damaging to corn plants. Corn earworm moths make lengthy annual northerly migrations which, if monitored, can provide growers with a warning. Unfortunately, aside from toxic sprays, there is nothing that we know of which will prevent the moths from arriving and laying eggs. There are controls for the larvae, though. The pale tan and dark striped larvae, which grow five centimeters, consume corn silks, then follow those silks into the husks, ultimately munching on the ear of corn’s kernels. Much of the damage is cosmetic and can be cut away, but consumers can be picky and will often refuse to buy affected corn. Moreover, the larvae expel visible fecal matter as they feed and move, making their presence even more obvious. To control these pests, Bacillus thuringiensis (K) (Bt) variety Kurstaki, can offer limited control. Parasitic Nematodes can also parasitize these pests if injected between the husk and the ear, but this method of control would not be an option in all but the smallest and earliest of outbreaks-it’s not realistically a viable solution.
These one centimeter beetles come in two forms: one is yellow with black stripes; the other is yellow with black spots. They are known as striped- and spotted-cucumber beetles, respectively. Unlike many beetles, their larval forms are found on the foliage portions of plants. Their larvae, therefore, which can be impacted with spined soldier bugs, Podisus maculiventris, cannot be thwarted by Parasitic Nematodes. Their pupae, though, which do use the soil as their protected development grounds, can. The larvae and adults munch on the leaves of many plants causing ragged feeding holes.
These grayish, black one centimeter beetles are top candidates for the World’s Ugliest Bug Award. And the damage they cause to fruits such as plums and apples isn’t any prettier. The adults feed on leaves, buds and flower petals, sometimes cause fruit deformities. They then lay their eggs in crescent-shaped wounds-which they make with their pointed, weevilish mouthparts, in any fruit which does develop, and the resulting larvae feed from within. The larvae cause the fruit to rot on the stem, develop grotesque deformities, and sometimes drop to the ground. Curculios are one of those pests which seem to defy the use of non-chemical controls. What may help is the use of repellent products such as garlic or capsicum pepper-based products or, perhaps, neem-based formulations.
Previously discussed in the Soil Pests page, these pests warrant a second mention here. Cutworms are the large (up to five centimeters) larvae of several species of moths. They live near the base of plants they’ll consume as they grow up — storing energy for pupation. Cutworms come to the soil’s surface at night, wrap themselves around the stem of their target plants — which are usually a new, tender — stemmed seedlings — and proceed to girdle them. Gardeners often find cutworm damage the morning after the pests’ feeding binge in the form of plants lying on their sides. Some control can be obtained from azadirachtin, the active ingredient in neem-based products. Parasitic Nematodes, are an excellent way to control these pests.
European Corn Borers
As their name implies, these are mostly pests of corn. The pestiferous stage of these moths is as larvae. The adults lay eggs on the plants and the resultant tan larvae, which can grow to 3 cm., burrow in the ears and stems expelling frass as they go. The stem feeding may cause plants to collapse; the ear feeding causes unsightly damage to the ears. Realistically the damaged portions can be cut away without ill-effect. But many people, being what they are, find the damage unacceptable are not willing to pay for tainted corn. Fortunately there are controls for these pests which work. Bacillus thuringiensis (K) (Bt) variety Kurstaki in a granular form, if applied appropriately, can effectively control these pests. If coupled with the use of moth-egg parasitoids such as Trichogramma brassicae, and performing a proper cleanup and disposal of affected plants at year’s end, control can be easily obtainable. Additional control can be obtained from azadirachtin, the active ingredient in neem-based products. Parasitic Nematodes can also parasitize these pests if injected in the bored holes, but this method of control would not be an option in all but the smallest and earliest outbreaks — it’s not realistically viable.