Insects that Attack Plant Roots
Insects that attack the roots of plants, destroy those plants' ability to gather nutrients. They are are also highly destructive of root crops and are a major problem in lawn care. Control by hand-picking is impossible. However, most are subject to an organic means of attack. Introduction of milky spore disease is an effective means of controlling these destructive insects.
White grubs are the "C" shaped larvae of various beetles. They devour the fibrous roots of grasses, strawberries, and other plants. They can be controlled with milky spore disease.
Raspberry Cane Borer,
also called a crown borer, are from eggs laid in a girdled portion of the cane near the top. Hatched larvae work their way down the cane until they finally feed on the roots. An effective means of dealing with the crown borer is to prune the crown of affected plants as soon as they are identified (before the borer has a chance to start working its way down the cane). Then destroy the pruned crowns. They are also fond of blackberries. (The raspberry cane borer can also be classified as a stem invading insect.)
Root maggots are the larvae of small flies (less than one-half cm - about 1/5th of an inch) that attack the roots of many plants, including cabbages, carrots, and radishes. In numbers they can cause the entire plant to wilt and die. Their attack can be an opening for diseases such as black rot. The female egg layers are attracted to freshly tilled soil, so cover these areas with floating row covers if possible. A strong paper collar can help protect seedlings.
Wireworms are the larvae of click beetles (Agriotes lineatus). They like to eat germinating seeds in the soil and to destroy young seedlings. They are quite fond of potatoes and other root crops. Wireworms spend four years underground before they pupate to become the click beetle. The beetle itself will sometimes feed on folliage. To control wireworms, frequent tilling can expose them to birds. The nematode Heterorhabditis megadis will also attack wireworms.
The Mole Cricket is a brownish insect that resembles a mole from the front, with shovel-like forelegs and two antenae extending from between its eyes and nose. It grows to be 2-5 centimeters (1-2 inches). It has wings and may fly or scurry. It can jump, but does so awkwardly. The mole cricket is actually a hunter and a scavenger. He searches for other insects to eat, but will also eat roots. He searches for food mainly by tunneling up to twenty-feet per day and in doing so can loosen the soil around plants, especially turf plants. As the insect likes sandy soil, this can cause the roots to dry out in sandy areas. Limited control can be achieved by applying entomopathogenic nematodes.
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