Illinois IDOA Amends Lymantria Dispar Quarantine

Illinois Department Of Agriculture Amends Lymantria Dispar Quarantine

Springfield, IL (STL.News) The Illinois Department of Agriculture (IDOA) announced two additional northern Illinois counties will be placed under quarantine to control the spread of Lymantria dispar, the destructive pest historically known as “gypsy moth” that destroys trees and shrubs.

Boone (Belvidere) and Winnebago (Rockford) counties in north central Illinois will join Cook, DuPage, Kane, Kendall, Lake, LaSalle, McHenry, and Will counties in the Department’s quarantine order.  Lake County was the first county in Illinois to be quarantined, which was established in 2000.

“The Lymantria dispar population in these counties has reached a critical level where steps need to be taken to protect other areas of the state from this destructive pest,” said IDOA Plant Regulatory Official, Scott Schirmer.  “These counties will remain eligible for participation in the Lymantria dispar control program, and the Department will continue to aggressively treat the leading edge of the infestation in these counties.”

Lymantria dispar is a non-native pest.  Large populations of the pest are capable of stripping plants bare, leaving them susceptible to disease and environmental stressors.  Severe defoliation can cause tree death.  Unlike the emerald ash borer, another non-native pest, which feeds exclusively on ash trees, the Lymantria dispar is not a picky eater.  It will devour almost anything leafy and green as it feeds on over 250 species of plants, but especially prefers oak and willow trees.

Under the quarantine, all nursery and lumber products must be inspected or certified before they can be transported out of the ten counties.  In addition, residents of these counties must personally inspect vehicles, tents, outdoor lawn furniture, bicycles and other outdoor items for Lymantria dispar egg masses, live moths and caterpillars before taking them from the quarantine zone.

Anyone convicted of illegally removing prohibited items from the quarantine area may be fined up to $500 and the items themselves must be either immediately removed from the non-infested area or immediately destroyed.

Male Lymantria dispar are brown with black chevron-like markings and have a wingspan of an inch-and-a-half.  Female Lymantria dispar are slightly larger and typically white or cream-colored with similar markings.  The females cannot fly because of the weight of their eggs.

IDOA will hold six open houses to explain its most recent plan to treat parts of northern Illinois for the destructive Lymantria dispar.  Infested sites will be treated with applications of either BtK (Bacillus thuringiensis var. Kurstaki), a naturally-occurring bacteria used by gardeners as an environmentally-friendly alternative to chemical pesticides, or mating disruption (MD), a Lymantria dispar-specific pheromone that acts as a sexual attractant and prevents male Lymantria dispar from breeding.

Anyone with any questions regarding either treatment method is encouraged to attend an open house where any and all questions will be answered.  Presentations are scheduled as follows to discuss and answer any questions about treatments in the surrounding areas.

Maps of the treatment sites and information on US Forest Service’s the Slow the Spread program can be found at: