Rock County, WI
Home MenuSpongy Moth
Spongy moth (Lymantria dispar, formerly known as gypsy moth) has been established in Rock County since at least 2006. The DNR aerial spray program was de-activated on non-DNR lands in 2017. Management of spongy moth infestations is up to residents and local property managers.
Spongy moths, caterpillars, and egg masses are commonly brought onto properties on firewood, vehicles that travel through infested areas, and items from an infested property (trailers, outdoor furniture, etc.).
Spongy moth caterpillar (above). Note yellow head, red and blue dots. Some may have brown or gray tint. They do not make webs. Caterpillars hatch in late April, by late May and June they resemble the photo. By July, caterpillars have pupated then emerged as non-feeding short-lived moths.
Spongy moth egg masses, August - April. Viable masses are somewhat firm and have a texture like suede, not rough or papery. Each mass contains 600 - 800 eggs that hatch in late April.
(Photo credits - WDNR).