Insect damage? It might be gypsy moth caterpillar or fourlined plant bug

stages of Gypsy moth
Gardeners have been seeing damage from Gypsy moths this year. There are actions you can take next year at various stages of the moth’s life cycle. At left are the egg masses. Current year egg masses are hard and velvety to the touch; older ones are soft because the eggs have hatched. At center is a caterpillar, which can grow to about 2 inches in length. Caterpillars have five pairs of raised blue spots followed by six pairs of raised red spots along their backs. At right are adults. The female is larger and white while the male is smaller and brown. From left, photos are courtesy Milan Zubrik, Forest Research Institute – Slovakia, Bugwood.org; Jon Yuschock, Bugwood.org, and USDA APHIS PPQ , USDA APHIS PPQ, Bugwood.org

by Connie Oswald Stofko

You may have seen damage to your plants recently and not known what was causing the damage.

Here are two possibilities: gypsy moth caterpillar and fourlined plant bug.

The worst is over for this year, but you should be on the lookout for them next year.

Below is some general information on Gypsy moth caterpillars and fourlined plant bugs.

If you have more questions about damage to plants or if you want an identification of an insect you see in your garden, contact the Master Gardeners in your area. They will be able to help you.

Gypsy moth caterpillar

“We had higher than normal calls on Gypsy moth caterpillar damage in localized areas this year,” said John Farfaglia, extension educator with Cornell Cooperative Extension in Niagara County.

This often occurs in 6-to-7-year cycles and can be very localized, he said.

In some areas, the Gypsy moth caterpillar causes significant defoliation of deciduous trees, and sometimes evergreen trees such as blue spruce as well. At the same time, other locations are untouched.

The feeding damage is now over for this year, he said.

Next year, start looking for egg masses before mid-April. You can scrape the egg masses off. There are steps you can take at other stages of the moth’s life cycle, too.

See more details on what to do next year on this factsheet from the Insect Diagnostic Lab at Cornell University.

Also see more information on the Gypsy moth from the New York State Department of Environmental Conservation.

The Cornell Insect Diagnostic Lab has a good fact sheet on this if you need more information.

Fourlined plant bug

fourlined plant bug from Bugwood
Adult fourlined plant bug. Photo courtesy Johnny N. Dell, Bugwood.org

Damage from the fourlined plant bug (Poecilocapsus lineatus) is past its peak now but was common this year,Farfaglia, said.

This insect has a wide range of host plants, according to this factsheet from the Insect Diagnostic Laboratory at Cornell University. They include:

  • Shrubs, such as amur maple, viburnum, currants and gooseberries
  • Many herbaceous plants such as chrysanthemum, dahlia, delphinium, lupine, peony, phlox, snapdragon, daisy, mint, sunflower and zinnia
  • Many garden vegetables
damage from fourlined plant bug courtesy Bugwood
Small circles of dead leaf tissue indicate the presence of fourlined plant bug damage. Photo courtesy John A. Weidhass, Virginia Polytechnic Institute and State University, Bugwood.org

Next year, watch for signs of damage starting in late May or early June. There will be small brown spots where feeding has occurred, about 1/8 inch in diameter.

Control measures are most effective when applied from early June through July, according to the factsheet. Adults can migrate to susceptible crops and plants from mid-June through July.

For plant bugs on particular ornamentals, insecticidal soap or other insecticides are labelled for you.

For any edible crop, check the product label first. Make sure that plant bugs are listed for the crop you want to treat. If not, don’t use that pesticide!

For edible crops you will also find a “days to harvest” interval listed. That’s the period of time you must wait after treating the crop until you harvest the edible portion.

See more details about the fourlined plant bug here.

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