Caseload at the UW Insect Diagnostic Lab (IDL) is currently very high. A summary of fruit crop insects reported to the lab in June as well as important insect trends can be found below:

Spongy moth (formerly known as “gypsy moth”): Spongy moth caterpillars are now large and very damaging in much of the state.  In far southern Wisconsin, caterpillars are pupating and adults are appearing—marking the end of the damage for the year.  In northern Wisconsin, caterpillars will remain active for several weeks.  Most reports of significant damage have recently come in from southeastern and southcentral Wisconsin.  Growers in northern Wisconsin should continue to monitor as significant defoliation was noted in northwest Wisconsin last year.

Rose chafers: In mid-June, reports of rose chafers (Macrodactylus subspinosus) began coming into the UW Insect Diagnostic Lab from parts of the state with sandy soil.  Many of these reports have come in from central and east-central Wisconsin.  Rose chafers are native scarab beetles that feed on, and skeletonize, many of the same plants as Japanese beetle.  Grapes and tree fruits are common host plants. 

Japanese beetles: Japanese beetle adults are starting to emerge in southern Wisconsin and we’ll see more in the coming weeks.  Last year, Japanese beetle activity was relatively low in most parts of southern Wisconsin, although high activity was reported in the Sheboygan area.  Interestingly, the IDL saw an uptick in reports of adults and damage in northern Wisconsin last year.  Only time will tell what Japanese beetle numbers are like this year—stay tuned!

Brown marmorated stink bug:  In late June I received my first confirmed case of brown marmorated stink bug nymphs in south-central Wisconsin.  Growers with a history of BMSB in their area should have these on their radar as juveniles are becoming active.  Nymphs will gradually become larger and will become adults in late summer and early fall.

Plum curculio: I’ve had many samples with plum curculio damage from around the state.  Most of these have come in from home fruit growers unfamiliar with the management of that pest.

Aphids: Aphids remain one of the commonest insect issues being reported to the UW Insect Diagnostic Lab this year.  I’ve recently had reports of aphids on fruit trees, especially apple cherry trees from southern and western Wisconsin.  At the same time, I’ve noticed an increase in photo submissions to the diagnostic lab that also showed evidence of natural enemies such as lady beetles, lacewings, hover fly larvae, and parasitoid wasps.  These beneficial insects can often help “turn the tide” over the course of a growing season. 

Spider mites: Ove the last few weeks, I’ve received many reports of spider mites from around the state.  Spiders mites can thrive in hot and dry conditions, so continued drought could create additional problems for growers.  Certain insecticides (e.g., carbaryl and imidacloprid) are known to induce spider mite problems, so growers should keep this in mind when selecting insecticides.

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 aphids, Brown Marmorated Stink Bug, Insect Diagnostic Lab, insects, Japanese Beetles, PJ Liesch, Plum curculio, Rose chafer, spider mites, spongy moth.