Insect

Eastern tent caterpillars and forest tent caterpillars emerging soon

If the weather warms up a bit, we could see eastern tent caterpillars (Malacosoma americanum) and forest tent caterpillars (Malacosoma disstria) hatching before the next forest health newsletter. These are both early spring caterpillars and hatch very soon after bud break.

Web nests and caterpillars will be small at first. Eastern tent caterpillars with pen.

Eastern tent caterpillars with pen. Web nests and caterpillars will be small at first.

Eastern tent caterpillar will make a web nest that can often be seen on wild black cherry along roadsides, although they also like to feed on crabapple, apple, and a few other species. Forest tent caterpillar does not make a web nest and prefers to feed on aspen and oak.

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Box elder bugs and lady beetles become active as weather warms.

Multicolored Asian ladybeetles have a range of colors and spot numbers.

Multicolored Asian ladybeetles

If you had box elder bugs or multi-colored Asian lady beetles congregating on your house last fall, you’re probably starting to notice them appearing in your house again as the weather warms this spring. Last fall they were able to find a place on/in your house to overwinter and now they are attempting to leave your house to head back into the fields where the beetles, like all ladybugs, will feed on aphids and the box elder bugs will feed on the sap of certain trees.

Continue reading “Box elder bugs and lady beetles become active as weather warms.”

New invasive insect: brown marmorated stink bug

The invasive brown marmorated stink bug (BMSB) is establishing in Wisconsin. BMSB is an agriculture, garden and home pest. Action to control populations may be needed in coming years.

An adult Brown Marmorated Stink Bug. Adults are ½ to 5/8 inch long, shield-shaped, mottled brown to gray with light and dark banding on the antennae and alternating light and dark spots on the end of the abdomen.

An adult brown marmorated stink bug. Photo by P.J. Liesch, University of Wisconsin-Madison Insect Diagnostic Lab.

BMSB is native to eastern Asia and was first officially found in the U.S. in 2001. The discovery of BMSB juveniles and the first noted pairs of mating adults in 2016 are continued signs that this invasive pest is establishing and reproducing in Wisconsin. We also had the first reports of BMSB feeding on plants, not just overwintering in structures. We expect populations will continue to increase in coming years.

 

A map of counties where BMSB has been confirmed or is suspected as of October 2016 was created by P.J. Liesch, University of Wisconsin-Madison Insect Diagnostic Lab and Bill McNee, Wisconsin DNR.

For information about how to identify BMSB and how to manage nuisance populations check out these publications.

Written by: Mike Hillstrom, forest health specialist, Wisconsin Dells (Michael.Hillstrom@Wisconsin.gov), 715-459-1371.

Unwanted in Wisconsin: hemlock woolly adelgid

Hemlock woolly adelgid is an exotic aphid-like insect that produces distinctive small balls of white wool at the base of hemlock needles.

White balls of hemlock woolly adelgid ‘wool’ on a hemlock twig in Maryland.

If you work around hemlock trees, keep an eye out for signs of hemlock woolly adelgid (HWA), an aphid-like insect that was introduced to eastern North America and is fatal to most hemlock trees.

HWA produces distinctive, small balls of white wool at the base of hemlock needles. Recently, a number of infestations have been found in western Michigan and there is a risk that the pest could spread across Lake Michigan into Wisconsin. Hemlock woolly adelgid has not been found in Wisconsin Continue reading “Unwanted in Wisconsin: hemlock woolly adelgid”