You Are Here: Management Updates 2000 Archive August 25, 2000

Date: August 25, 2000
Category: Insects
Subject: Scouting for White Grubs

The cool weather continues to mask insect damage, and in some cases delays insect development. We were sampling for Japanese beetle grubs in western Massachusetts yesterday. In "normal" years, we would expect to see mostly first and second instars at this time but yesterday all we found were some eggs and some TINY first instars (baby grubs). In fact some of the babies still had the egg casing attached, so they had only hatched within the past 24 hours or so.

What does this all mean??? At least for Japanese beetles, we are guessing that the cloudy weather all summer has put a bit of a crimp in their style, so perhaps the females have been less active during the daytime, when they normally would be moving about. And of course the soils have been moist and cooler than normal, so that is holding things back as well.

We are not at all sure whether the same "delay" in development has been occurring with other species of grubs, like the European chafer. Given that the European chafer is a night-flier, it may have been less directly impacted by the cloudy weather that marked this summer.

In any case, now would be a good time to be scouting those areas that are usually attacked by grubs. Just remember that some species (like the Japanese beetle) are REALLY small right now, so get out your magnifying lens.

- Submitted by: Dr. Pat Vittum