Aerial spraying (Photo courtesy: Wisconsin DNR)
MARINETTE COUNTY, WI (WTAQ-WLUK) — Officials announced Wednesday that Marinette County is one of a half dozen properties statewide to undergo aerial spraying for spongy moth caterpillars.
The six identified treatment sites contain high-value trees at DNR properties in Columbia, Marinette, Sauk and Walworth counties.
928 acres will be treated with an aerial spray of Foray, “a bacterial insecticide containing Bacillus thuringiensis var. kurstaki.” 255 of those acres are located at Governor Earl Peshtigo River State Forest.
Spraying will occur between early May and early June. Exact dates and times depend on caterpillar development and weather conditions.
The DNR intends to avoid spraying high-use properties during the extended Memorial Day weekend if spraying has not occurred. Wisconsin’s first known spongy moth egg hatch was reported on the morning of April 17, making it likely that aerial treatments in southern counties will be completed well in advance of the Memorial Day weekend.
Local governments, law enforcement, schools and medical facilities will be notified before spraying begins.
Aerial spraying helps reduce damage caused by spongy moth caterpillars, which feed on many trees and shrub species — stripping the trees of their leaves and potentially killing them. Experts say healthy trees can endure a few years of heavy defoliation before tree mortality occurs.
Healthy trees typically produce a replacement set of leaves a few weeks after defoliation. However, this process uses energy reserves and weakens the tree, making it more vulnerable to mortality in combination with other insects, diseases or drought stress.
Spongy moth outbreaks occur every five to 10 years. Last year, Wisconsin saw a record amount of spongy moth defoliation, impacting about 375,000 acres.
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