I have not received many calls complaining about Japanese beetles so far this summer, but I have seen more activity in my own yard (wild grapes, among other things) than I did last year. Of course we got a lot more rain in May, June, and early July this year than last year, so conditions are good for beetles to survive well. But I had wondered whether the extremely dry conditions of last year would translate into lower grub populations going into the winter (and surviving this spring). Not so much ...
During my travels I have seen Japanese beetles that have been parasitized by the "winsome fly" (Istocheta aldrichii) - around the Amherst area and, more recently, about an hour north of Portsmouth NH on the NH/ME border. It is always encouraging to see parasitized beetles showing up in new places. And it was especially satisfying to see that the parasitized beetles I held in my hand clearly were not going to survive more than another day or two.
Hotter and drier weather
Just a reminder that some areas have not been receiving much rainfall the last few weeks. As we experience hotter temperatures and drier conditions in August, some turf may appear to be entering dormancy. Don't forget to check and see whether chinchbugs or billbugs are active in those areas. (There is not much you can do to control billbugs at this point, but you can reduce chinchbug populations any time from late May to early September with a pyrethroid, if necessary.)
Annual bluegrass weevil
As expected the annual bluegrass weevil is still quite active. Samples earlier this week from near Hartford revealed several small larvae, along with large larvae and pupae. My best guess is that the large larvae and pupae reflect the end of the second generation, while the small larvae could possibly be the opening salvo of a third generation.
Again the higher temperatures and generally lower rainfall imposes stress on the turf, so it will be less able to withstand ABW activity. Keep monitoring, and be prepared to take action if you see the number of small or medium larvae increasing.
Submitted by: Dr. Pat Vittum