With the growing season wrapping up in Wisconsin, caseload at the UW Insect Diagnostic Lab has steadily decreased over the last two weeks.  A summary of relevant insects and fruit crop pests submitted to the UW Insect Diagnostic Lab over the last two weeks can be found below:

Multicolored Asian lady beetles: The very pleasant weather last week led to a surge of activity of multicolored Asian lady beetles around the state.  While Asian lady beetle numbers have varied around the state the past few years with higher populations generally seen in more northern parts, 2020 saw high activity across Wisconsin. 

Last week’s flurry of activity was related to the Asian lady beetle’s shelter-seeking behavior in preparation of winter.  Nighttime temperatures near freezing prime these insects to seek shelter and on days where the temperatures climb into the 60’s or 70’s they can be particularly active.  In their native range, these insects often go to exposed cliffs to overwinter, but homes and other structures work just as well for their needs. 

Brown marmorated stink bugs: Similar to multicolored Asian lady beetles, I had a bump in reports of brown marmorated stink bugs last week.  Most of these reports came from south central and southeastern Wisconsin, where BMSB is well established.  Growers that spotted these recently should have this pest on their radars for 2021.

Yellowjackets and paper wasps: Activity from yellowjackets and paper wasps has declined over the last two weeks, although they were still being spotted scavenging on damaged fruits.  These insects have annual colonies which naturally die out in the fall, so any remaining wasps have little time remaining.  Only specific females from each colony spend the winter—these will emerge as the new queens next year and will attempt to establish nests in spring.

This article was posted in Insects and tagged Brown Marmorated Stink Bug, Insect Diagnostic Lab, insects, multicolored Asian lady beetle, paper wasps, yellow jackets, yellowjackets.