A Listing of Other Plant Pests: N-S


Nematodes?! Sound familiar? Haven’t we read about them somewhere? That’s right, parasitic nematodes. But aren’t they good ‘todes? Yes, the parasitic ones we’ve referenced are, but not all nematodes were created equal. Some are good as we can utilize them to our advantage. Others can physically injure humans. And some are root pests. There are, perhaps, more nematodes on earth than any other multicellular organism. Overall, few are evil. Nematodes vary immensely in size from one species to the next. These pestiferous nematodes tend to be on the small end of the scale, ranging from much less than one millimeter to several millimeters. They live in the soil feeding on root structures and the detritus resulting from their behavior. Their feeding causes all sorts of plant disfigurement and nasty growths — on both the roots and above-ground plant parts. Pestiferous nematodes are extremely difficult to get rid of. There are powerful chemicals designed to kill nematodes (and these will kill the good ones, too), but they really should be used only if all other means of control do not work. There are only three things which have proven themselves capable. The first is to border-plant the field or garden with a nematicidal marigold bush which repels nematodes, Tagetes minutum. These commercially available (by seed) marigolds, if planted densely enough, can keep an uninfested plot clean. The second would be to heavily enrich the soil with clean, composted organic matter. This is to make soil conditions less favorable for the bad nematodes. The third treatment of which we know, one that is safer than most — environmentally speaking. This is a granular product made of, basically, crab shells. It is the natural chitins in the shell material which makes rough the lives of these pests. Other plans to implement if you’re dealing with nematodes would include a defense of crop-rotation and an offense of soil sterilization (if possible). Unfortunately, and this will seem like a first, parasitic nematodes do not impact the lives of their evil brethren. But good nematodes don’t parasitize earthworms, either, so there’s bad news and good.

Onion Maggots

Onion Maggots are the larvae of nondescript seven millimeter stereotypical fly-looking flies. The adult flies lay their eggs at the base of certain allium- or onion-family plants. The eggs hatch and the off-white larvae tunnel into onions-often causing extensive damage and set rots. Their feeding can literally wipe out a crop, especially one located in a cool and moist environment. Row covers can keep out the flies, but some may develop within the confines of the cover. (This is one of the reasons why crop rotation is such a wise choice in gardens and agricultural crops.) Garlic and capsicum wax products may also help keep the flies away, especially if they are applied on or near the soil’s surface. Then again, garlic may be an attractive odor to these particular flies. Parasitic Nematodes can effectively control these pests if they are applied at the right time to target larval forms before they delve too deeply into the onion, and pupal forms in the fall and spring.

Saw Flies

As their name implies, these pests are tiny five millimeter flies. They don’t saw down trees, though. The damage they cause come from their larvae which can decimate leaves of many trees. Current non-chemical control methods include feeding-disruption techniques such as blasting larvae from the leaves they are destroying with streams of water. This, however, is extremely impractical. Other controls may include the use of Parasitic Nematodes as the larvae of these flies pupate in the soil. Other Green products, such as azadirachtin-containing neem-based products, may offer some relief, but check the label for the appropriate listing before making a purchase of said goods.

Slugs and Snails

Everyone is familiar slugs and snails. Slugs are slime-covered creatures which pave a path of slime as they go and typically spend daylight hours nestled under a leaf liter, wood debris, or rocks and pavers. Snails are very similar to slugs, except they carry a shell in which they can hide. Snails, too, spend their days tucked away, but can do so in a wider variety of places since they carry their primary residence with them at all times. Both creatures vary considerably in size, ranging from a few millimeters to several centimeters in length. They also have an affection for plants. Both of these pests come out at night and chew large sections from plants’ leaves and can be very damaging. Some people claim egg shells or diatomaceous earth (DE) sprinkled around plants can deter these slimy creatures. However, slugs (especially slugs) and snails, prefer moist conditions and DE, being a powerful absorptive agent, loses its punch in such conditions. Beer traps have also been known to work so say some. These are basically dishes like pie tins and such with beer in them. These guys go for it, trying to grab a brewski, they fall in and drown. Hic! As another option, copper tape or copper banding is extremely effective in some situations (as may be copper mesh). The element, combined with the creatures’ slime, creates a electrolytic charge which is powerful enough to deter them if it is applied correctly, is appropriate to the circumstances, and is kept as clean as possible. Metaldehyde-containing baits have been successfully used for years. They’re bad news, though, environmentally speaking. Fortunately, there are some new products available which are highly regarded for their safety and earth-friendliness, their ease-of-use, cost, longevity and effectiveness. These newer baits contain iron phosphate. This substance works like the other baits in that it is eaten by the pests and they go away and die. It is different, though, in that remaining pellets break down into non-damaging, nutrient-containing by-products.

Sow Bugs

Rolly-pollies, pill bugs: The names may be different, but the shape is the same. They look like one centimeter (more or less) blunted armadillos with antennae. Color varies from all shades of grey, to brown, to black, with exotic shades of blue thrown in for good measure. You touch them and they curl up into little balls. They are odd creatures, but not strange insects; they are strange crustaceans. They live under leaf litter, plant debris, within organic matter, and under logs and rocks. They are not terrible plant pests — especially if the plants you’re growing are well established and the sow bugs are in small numbers. If, however, you’re dealing with large numbers of these creatures, or if your plants are mere seedlings, sow bugs can become overwhelming. So what’s to be done? Upon talking to some people who’ve had to deal with them, some solutions were offered. One was a saucer of beer (like that which is sometimes effective for slug and snail control) used to lure and trap these “bugs”. Another simple remedy which was mentioned was to sprinkle corn meal in areas where these pests are seen. Our understanding is that they eat the stuff and can’t digest it. The general consensus has been that the corn starch disappears, the sow bugs thin, and the people who’ve tried it don’t really know to what it should be attributed. Another suggested the use of European quail. The person who suggested this uses these biocontrol agents in a conservatory which was once plagued with sow bugs. The sow bugs are kept in control by the birds. If the situation can tolerate the birds, why not? There many are other recipes for success-mostly baits to poison or trap these creatures. But if none of it works, flipping over logs and stones and debris every morning and simply squashing these pests will.


Ever see a plant which looked like someone spit of it? The spit was probably from spittlebugs. They produce and live in this frothy excretion. The bugs themselves are rarely seen, but average about six millimeters in size and are usually pale yellow in color. They do suck plant juices and, if in abundant numbers, may cause some stunting of plants, but we’ve never heard anyone truly complain about feeding damage or virus transmission as of a result of the presence of these insects. Most comments are directed to the discomfort of offering plants for sale with globs of spit tucked into the branches. Though it is nothing some hose-water can’t take care of. In some crops spittlebugs’ er, nests, are commonly seen. Strawberries is one. You can actively disrupt them with hose water, and yields were excellent.

Spruce Budworms

The larvae of these three centimeter nondescript gray-colored moths are serious pests of conifers. The caterpillars tunnel into needles, twigs, buds and cones of several types of coniferous trees causing extensive damage yearly to conifer-offering nurserymen. Also affected are those who grow Christmas trees and those in the lumber industry. Fortunately, Bacillus thuringiensis (K) (Bt) variety Kurstaki, if sprayed at the right time, will control these pests. Do, however, expect to have to spray a lot of the bacteria-containing substance, especially if you have a large stand to treat (and this is likely with these caterpillars). Trichogramma spp. moth-egg parasitoids may also impact populations of this pestiferous moth species. Again, though, timing will be important. Other non-chemical remedies, to the best of our knowledge, do not exist. Good luck.

Squash Bugs

Growing to two centimeters, these dark patterned shield-shaped true bugs can be very damaging to squash, melons and others of that family. Their feeding will cause whole shoots to wilt and eventually die back completely as they drain away the plants’ life-giving juices. We wish we could tell you about all kinds of excellent controls for squash bugs, but we can’t. They have no commercially-produced natural enemies. Nor are they taken down by Parasitic Nematodes or Bacillus thuringiensis (Bt) strains. Row covers are effective if used until pollination is needed and are placed over planting spaces free of leaf litter and plant debris. Experimentally, we suppose, spined soldier bugs, Podisus maculiventris, could be lured or introduced into a the melon patch — they’re very opportunistic and may predate the squash bugs’ nymphs, but we’re not sure. Moreover, products containing garlic or capsicum wax may repel these pests, or deter their feeding.

Squash Vine Borers

The larvae of these moths are not just interested in squash plants as their names implies, they love many of the cucurbits. The moths are red and gray-black and quite large at approximately three to four centimeters in length. The adults are not damaging, though. They lay their eggs near the base of their preferred plants, and the resulting larval forms burrow into the plants. It is they who cause the stem wilting and dieback. Row covers provide a means of preventing the moths from laying their eggs. However, since the plants require pollination, the covers must be removed when flowering begins. Parasitic Nematodes provide another avenue of control, but must be introduced at the proper time — as the eggs are hatching but before the larvae have a chance to bore into and enter the crown and stems. If your timing is not right, you can still gain the upper hand by injecting the nematodes into the affected stems by way of the bored holes, but this is not a practical solution in anything other than a small scale plot. The injection method of applying nematodes is very time-consuming. Speaking of time consuming, it has been recommended in some books to perform surgery on affected plants by slitting the stem and physically removing the larvae. Additional control can be obtained from azadirachtin, the active ingredient in neem-based products.

Strawberry Root Weevils

These black, armored weevils grow to about eight millimeters and can be major strawberry pests. Moreover, they can impact other fruits, including cane berries, grapes, fruit trees and even some conifers. Like black vine weevils, these insects distinctively notch the leaves of their victims. Additionally, their presence is also felt in the root zone where the larval stages of these pests also feed. Also like black vine weevils, on a very positive note, strawberry root weevils are efficiently controlled with Parasitic Nematodes. Temporary control, due to pollination requirements, can be obtained in certain crops by covering them with a floating row cover. However, this may contain those weevils which began life in the soil of the root zone of the covered plants. It is, therefore, necessary to treat with nematodes prior to covering the plants. Other goods, like garlic and capsicum wax sprays may help repel these pests or deter them from feeding.

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