Overall caseload at the UW Insect Diagnostic Lab has been high over the last two weeks.  A summary of recent fruit crop insects reported to the UW Insect Diagnostic Lab can be found below:

Gypsy Moth: I’ve had many reports of gypsy moth caterpillars from across Wisconsin, other than the westernmost counties bordering Iowa and Minnesota.  South central Wisconsin and northeastern Wisconsin account for the greatest number of recent reports at the UW Insect Diagnostic Lab. Overall, 2021 seems to be shaping up to be a good year for gypsy moth and the dry conditions will likely help them in many areas.  In rainy years, gypsy moth caterpillars can be killed off by an introduced fungal disease (Entomophaga maimaiga), but dry conditions tend to inhibit fungal activity.

Eastern Tent Caterpillar: I continue to get reports of eastern tent caterpillars from many parts of the state.  By now, many of the caterpillars are nearing maturity and will be pupating in the near future. 

Speckled Green Fruitworm: Similar to my last report in WFN, I continue to see some reports of speckled green fruitworm from around the state.  These have primarily been from southern Wisconsin. 

Striped Hairstreak Caterpillar: I had a report of apple fruit damage caused by caterpillars of the striped hairstreak butterfly from southwestern Wisconsin.  This species is an occasional/minor pests of apples and damage is usually limited in scale.

Plum Curculio: By now, damage from plum curculio can be seen on developing fruits.  In the last two weeks I’ve had a number of cases of damage to apples and stone fruits.  Cases have primarily come in from southern and western parts of the state.  I also had a recent report of the related apple curculio from south central Wisconsin.

Codling Moth: I’ve had scattered reports of activity from around the state, primarily from backyard fruit growers.

Spindle Galls: Spindle galls can be common on stone fruits.  I’ve recently had several reports from backyard fruit growers around the state that had not encountered these galls before.  Although the galls look odd, they are essentially a cosmetic issue for plants and treatments are not effective against them.  These particular galls are caused by tiny mites from the Family Eriophyidae. 

Brown Marmorated Stink Bug: Reports of brown marmorated stink bugs continue to come in to the UW Insect Diagnostic Lab, especially from southern parts of the state. Most cases involved BMSB adults.  However, eggs and first instar nymphs have recently been observed in south central Wisconsin.  As the nymphs get larger, they’ll become more noticeable.  Typically, I see reports of BMSB juveniles from late June onwards and they can become common in established areas in July, August, and September.

This article was posted in Insects and tagged Brown Marmorated Stink Bug, Codling Moth, eastern tent caterpillar, gypsy moth, Plum curculio, speckled green fruitworm, spindle galls, striped hairstreak caterpillar.