Archive for Thursday, October 6, 2005

The best cure for this pest nuisance: Turn off the porch light

October 6, 2005


Many times, people try to escape the bright lights and big city by taking a relaxing trip to the country. However, in the bug world, this trip has been turned around. A well-known pest in soybean fields is starting to show up around homes, drawn to the bright lights of the big city.

Green cloverworms spend most of their lives consuming agronomic crops. However, this year the adult moths can be found around town by the dozens. Here's what you need to know about this country visitor and what you can do to stop him:

Green cloverworm larvae have been feeding on alfalfa, beans, clover, cowpea, soybean, strawberry, vetch, many common weeds and other legumes all across the Midwest for the past three months. The larvae are pale green with one or two white stripes extending down each side of the body, and three pairs of prolegs in the middle of the body. They wiggle violently when squeezed, an action that most other caterpillars do not exhibit. Green cloverworms overwinter either as pupae or adult moths.

In spring, moths become active about the time clover becomes abundant. After mating, the females lay one egg at a time on the underside of leaves of the host plant. Eggs hatch in less than a week. In soybeans, young larvae will feed anywhere throughout the soybean plant, but older larvae confine their feeding to the upper one-third of the soybean canopy. After feeding for about three to four weeks, larvae drop to the ground, burrow into leaf litter or soil, and pupate. The pupal stage lasts about 10 days. Two to three generations per year can occur in our area.

It's the adult moth that is causing all the trouble this year. The adult is dark brown to black with a triangular shape. It's drawn to outdoor lights and often finds its way inside homes when doors or windows are open. Neither the adult or larvae will damage landscape or garden plants. Nor does it feed on homes or home furnishings.

Diseases frequently suppress green cloverworm populations. However, this may not occur until late in the season.

Many entomologists consider the green cloverworm a valuable food source for beneficial insects and diseases. Adult moth control is virtually impossible due to new moths replacing those that are killed. Simply turning off the outside light for a few weeks may help make your home less attractive. This is one of those nuisances that eventually will take care of itself as the populations decrease.


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