With leaves and flowers appearance, caseload is beginning to pick up at the UW Insect Diagnostic Lab. A summary of fruit crop samples submitted to the IDL thus far in 2025 can be found below:

Spongy moth & eastern tent caterpillar: Both of these caterpillar pests recently emerged in southern parts of Wisconsin and activity will begin in more northern areas in the next few weeks.  Both can be pests of fruit trees, so growers should be monitoring for these.   

Aphids: Aphids have recently (i.e., last two weeks) been reported on a range of landscape plants and crops.  Growers should keep a general eye on aphids.  Due to their high/rapid reproductive strategy, aphid populations can often get a “head start” at the beginning of the growing season, but are usually brought under control over the course of the season as natural enemies (i.e., predatory and parasitic insects) “catch up”.  Care should be taken to scout for beneficials if aphid populations are observed as spraying may not be needed.

Slugs and earwigs: Last year (2024) was a good year for both slugs and earwigs due to above-average rainfall in spring.  Some reports have already come into the UW Insect Diagnostic Lab this spring.  Growers of low-growing fruit crops, such as strawberry) should scout for these pests, especially if rainy weather is forecasted, fields have heavy plant residues, heavy soil, and/or lots of weeds.

Spider mites: Spider mites have had highly variable populations in Wisconsin the last few years due to yo-yoing weather conditions.  With average or above-average rainfall, populations of these mites are typically held in check.  However, these mites can thrive if dry, droughty conditions occur.  Spider mites can feed on a very wide range of host plants/crops, including a variety of fruits. Growers should rely on their field histories and scouting efforts to assess mite activity.  Pay particular attention if dry conditions are forecasted.

Lygus / Tarnished plant bug:  Tarnished plant bug adults have been active for some time, with the first reports coming into the UW Insect Diagnostic Lab several weeks ago.  Since these overwinter as adults, they can become active early in the season.  Tarnished plant bug can be common and widespread, but can be a notable pest of certain fruit crops such as strawberry.  They can also be an occasional issue in tree fruits, such as apple and pear.  Growers should keep an eye out for activity while scouting. 

Bees and other pollinators: In much of the state, early season pollinators are active at the moment, with many recent sightings of bumble bees, honey bees, mason bees, mining bees, and other pollinators reported to the UW Insect Diagnostic Lab.  With the importance of pollinators for fruit crop production, growers should be aware of pollinator activity in their area and take appropriate precautions to minimize risks to bees and other pollinators when implementing pest management efforts.

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 Insect Diagnostic Lab, insects, PJ Liesch.