New Invasive Insect Found In Wisconsin

A new invasive insect was detected in central Wisconsin this season by DATCP’s Forest Entomologist. The elm zigzag sawfly (Aproceros leucopoda) was observed on elm foliage in Portage County in July. This unexpected discovery marked the first Wisconsin observation of the elm pest and a new state record. Official confirmation was made by USDA-APHIS on July 30, 2024.

Its capacity to produce multiple generations each season, in combination with hitchhiking on vehicles, plants, and other outdoor items, has allowed the elm zigzag sawfly (EZS) to spread rapidly. Since the first North American (in Canada) report of EZS in 2020, this native East Asian insect has been recorded in several eastern and Midwestern states in the U.S. In Wisconsin, the July EZS discovery quickly led to reports in 20 more counties. The growing list of positive counties suggests it is established and widely distributed in the state.