The Homeowners Column

The Homeowners Column

Be on the Lookout for Gypsy Moth

Photo of Sandra Mason

Sandra Mason
Extension Educator, Horticulture
slmason@illinois.edu

Many things such as bulldozers and lawnmowers threaten the trees in our wild and landscaped areas, but some of the most difficult to control may be the alien invaders. Insects may crawl, fly, walk, roll, hitch rides in storms and even attach themselves to animals, but we humans have become a part of their travel system. People and their goods travel farther and faster than ever before. However, included in our travels are the plant and animal hitchhikers.

Bring an insect, plant or animal out of its native area and the results can be devastating. The natural predators and diseases that keep their populations down in their native areas don't come with them. There are usually no natural checks on their population growth in non-native areas.

Gypsy moths are one of the most destructive pests of forests and landscapes. The caterpillars have voracious appetites and can quickly defoliate neighborhoods and forests in the two months they feed. Gypsy moths originated in Europe and were brought to New England in the mid to late 1800s. They have remained a problem in the northeastern states, but have also become a problem in Wisconsin and Michigan.

Gypsy moths have also made their way into northern Illinois. Lake County was the first area of Illinois to be quarantined in July of 2000. When infestations are too large or numerous to be eradicated, the Department of Agriculture quarantines areas. Homeowners may notice little direct effect of a quarantine other than letting them know that gypsy moth is a problem in their county.

Everyone can help by knowing what to look for. Newly hatched caterpillars are about one eighth of an inch long and mostly dark brown to black. As they grow they develop blue and rusty red spots with tufts of hair. They usually feed in the treetops at night in May and June. However they migrate to the ground each day to protect themselves from heat and bird feeding. The adult moths are present in July and August. Females are tan and one inch and one quarter long with cream-colored wings. Females do not fly. The males are smaller, dark brown and are good fliers.

Oak trees are most susceptible, but gypsy moth caterpillars will feed on 500 other trees and shrubs if oak are scarce. The trees may not initially die from the caterpillar feeding but the feeding weakens the trees. Death may result from borers or environmental stresses of cold or drought.

What you can do to help stop alien invaders:

  • Be informed. We have an excellent brochure "Homeowner's Guide to the Gypsy Moth in Illinois." Copies are also available through U of I Extension at 1-800-345-6087.

  • If you travel in states or have just moved from states known to have gypsy moths, check vehicles, picnic tables and lawn furniture thoroughly for the tan hairy egg masses. A quick swipe with a putty knife can eliminate this hitchhiker. Females lay eggs on any convenient spot — such as firewood, fences, automobiles, and campers.

  • Don't tamper with the triangular cardboard boxes you may see around town. They are scouting traps for the male gypsy moth.

  • Don't transport firewood for long distances.

  • Don't transport any insect, animal or plant found in another area of the country no matter how cute it may be.

  • When the border patrol asks you about carrying plants, fruits or vegetables, smile when you declare that apple you have stowed away. The stops may seem time consuming or just plain ludicrous, but they are important.

  • If you live outside a quarantined area and find evidence of gypsy moth, do not try to treat the problem until you contact the Illinois Department of Agriculture's toll free hotline 1-866-296-MOTH(6684).

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