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Green
Cloverworm is common throughout the soybean-growing areas of the eastern
United States and the Great Plains, but seldom reaches pest status. Larvae of
this species feed on the leaves and, when abundant, can cause heavy defoliation
of the bean plants. Because it attacks early in the season, however, plants
usually compensate for foliage loss before pods are set.
The larvae are pale green with two narrow white
strips along each side of the body. They are bare, slender, about 1 1/4 inches
in length when fully grown, and fairly east to distinguish from other insect
larvae by the number of prolegs on the abdomen (the short, fleshy legs along the
middle of the body). Cutworms and armyworms have four pairs, loopers have two
pairs, while the green cloverworm larvae have three pairs of prolegs.
Fortunately, green cloverworms usually are
controlled by a fungal disease. High humidity with warm temperature, favorable
for the development of the fungus, may be sufficient to reduce a high population
of green cloverworms.
Many
entomologists consider the green clover worm a valuable food source for
beneficial insects and diseases. This reservoir of beneficials often controls
pests of more economic importance later in the season. Treat only if defoliation
reaches 40% in pre-bloom, 20% during bloom and pod-fill, and 35% from pod-fill
to harvest.
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