UW-Madison/Extension Insect Diagnostic Lab Update – July 2nd, 2025
Caseload is currently high at the UW Insect Diagnostic Lab with 20+ cases daily. A summary of recent fruit crop samples submitted to the IDL over the last two weeks can be found below:
Aphids: Aphid reports continue to come into the UW Insect Diagnostic Lab from around the state. In fruit crops, aphids have most commonly been reported on foliage of cherry and apple. Growers should scout for beneficials in addition to aphids as natural enemies have been present and abundant in many cases.
Rose chafers: This native scarab beetle has habits very similar to the non-native Japanese beetle. Rose chafers are a pale beige color with orange legs. They feed on many of the same plants and cause similar skeletonization to Japanese beetle. Rose chafers are restricted to parts of the state with sandy soil and recent reports have come in from areas near the southern parts of the Wisconsin River, and well as central and northeastern Wisconsin. Rose chafers are typically active for approximately 3-4 weeks from mid-June to mid-July. Their activity starts to dip right around the time that Japanese beetles get going for the year.
Japanese beetles: The first reports of Japanese beetles have recently come in from southern Wisconsin. Growers should remain alert as Japanese beetle can be a notable pest of a wide range of fruit crops. Japanese beetles can now be found across much of Wisconsin, and their presence has become more noticeable in northern Wisconsin over the last 5 years.
Brown marmorated stink bug: First instar nymphs were recently reported in south-central Wisconsin. Growers should keep an eye out for juveniles while scouting.
Codling moth & plum curculio: A few cases of apples with damage from these insects (stings & oviposition scars) have come into the lab recently from southern Wisconsin.
Looking ahead: Expect Japanese beetle activity to increase over the next two weeks—especially if you have a history of this insect in your area.
Reminder about diagnostic support from the IDL: Growers and consultants in need of insect diagnostic services are always welcome to submit a sample to the UW Insect Diagnostic Lab. Lab services are provided free of charge. You can find additional information about the IDL here: insectlab.russell.wisc.edu
This article was posted in Insects and tagged insects, PJ Liesch, UW Insect Diagnostic Lab.