Aerial spraying for spongy moths to take place May 13-July 1 in Randall, Twin Lakes

From the Kenosha County Department of Public Works & Development Services:

This spring, the Kenosha County Department of Public Works & Development Services will be overseeing aerial spray treatments to control the significant presence of the invasive spongy moth in an identified outbreak area.

Spraying will occur along the east side of Highway KD north of Highway C in the Town of Randall and the Village of Twin Lakes.

This spraying will occur in two applications made three to 14 days apart, between the dates of May 13 and July 1. The timing of the spraying is dependent upon the development of the spongy moth larvae and local weather conditions, said Vijai Pandian, Horticulture Educator with Extension Kenosha County.

A low-flying helicopter will spray a biological pesticide called Bacillus thuringiensis var. kurstaki (Btk). Btk is a bacterium that occurs naturally in the soil. Like other bacteria, Btk forms spores, but unique to this species, it also forms protein crystals that are toxic to the susceptible caterpillars when ingested.

“Btk is not toxic to people or animals,” Pandian said. “Based on epidemiological studies and the long history of its use, there is no evidence that the application of Btk formulations causes any effects to people or animals in treated areas. It affects caterpillars, and only caterpillars, when they eat leaves that have Btk on their surfaces.”

Formerly known as the gypsy moth, the spongy moth (Lymantria dispar) is an established invasive insect that defoliates more than 300 species of trees including oaks, birch, lindens, crabapple, aspen and willows. During its last major outbreak, in 2010, nearly 347,000 acres of tree defoliation occurred in Wisconsin.

Prevention measures and other resources:

To help slow further spread of the spongy moth in Kenosha County’s current outbreak area, Pandian encourages property owners in Twin Lakes and Randall to use sticky barrier band traps to reduce the young caterpillar population in their trees.

More details are available in an informational piece from the UW-Madison Division of Extension, available at

A resource page with more information about the spongy moth and links to various related resources is available on the Kenosha County website, at

Anyone with questions about this effort may contact the Kenosha County Department of Public Works & Development Services at 262-857-1870.


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