Overall caseload at the UW Insect Diagnostic Lab has begun to decrease for the year, including reports of fruit crop insects.  Reports of fruit crop insect activity submitted to the IDL in late September and early October are summarized below:

Japanese beetles: Japanese beetle season has essentially wrapped up for the year.  Reports suggest that pressure seemed to be down this year in many parts of the state compared to last year.  However, it is noteworthy to mention that Japanese beetles have steadily increased their range in Wisconsin.  Japanese beetles are well established in southern and central parts of Wisconsin, with less activity in the north.  However, 2019 saw reports from northern areas, including Oneida, Vilas and Bayfield counties.

Brown marmorated stink bug: Sightings of BMSB juveniles have decreased over the last few weeks as late instar nymphs have transformed to the adult stage by now.  Stink bug damage to apples has been reported in several cases from southern and eastern Wisconsin.  BMSB adults will be trying to invade structures in the coming weeks as they seek out sheltered overwintering spots.

Spotted Wing Drosophila sightings continue to trickle in to the UW Insect Diagnostic Lab.  Although temperatures may be starting to dip for the season, SWD can continue to be active into the fall, so make sure to keep an eye on late season crops.  This pest is widely distributed around the state.

Social wasps, including bald-faced hornets, yellowjackets, and paper wasps are in a period of high activity.  These insects have annual colonies and are desperately searching for food in late summer and early fall.  While they are unlikely to cause damage to sound fruit, these wasps readily scavenge on compromised fruits that have been affected by other insects, disease, or physical/mechanical injury.  These wasps can also be an aggressive nuisance around workers at the time of harvest. 

This article was posted in Insects and tagged BMSB, Japanese Beetles, social wasps, SWD.