You Are Here: Management Updates 2006 Archive June 9, 2006

Date: June 9, 2006
Category: Insects
Subject: Annual Bluegrass (Hyperodes) Weevil, White Grubs

Annual bluegrass weevils
I just dissected six annual bluegrass weevils (collected earlier this week in Westchester County) to see what was going on, and was surprised to find two females who still had a couple viable eggs in their bodies. It certainly explains what we have been seeing all spring - a very long and drawn out egg-laying period. But we don't know why it has been so spread out this year. (About 70% of the weevils are females and 30% are males at this point.)

We have only seen two pupae out of several hundred insects so far, so it was highly unlikely that the adults we dissected were "new" ones. In fact, when I looked at the thorax of each weevil, it was fairly shiny because some of the hairs and scales have worn off. That is common with older weevils.

My suspicion is that some females got an early start on egg laying in early May, but then when the rains came, the air temperatures cooled and the soil temperatures did not warm up as quickly as usual. So any weevils that were a little late becoming active after overwintering would have been two to four weeks behind their speedier cousins.

What does all this mean for management??? Unfortunately, I think it means that this year will be even harder than usual to figure out what generation is present at any given time. Superintendents again will have to monitor conditions on their own golf courses and determine which stage is most prevalent, and then treat accordingly. (As a quick reminder, spinosad and trichlorfon have looked promising against larvae, while a pyrethroid or chlorpyrifos continues to work well against adults.)

Meanwhile all the rain has not been helpful! If the soil is saturated, you need to wait until things dry out a bit before applying an insecticide.

Grubs
We noticed that most of the oriental beetles at our site in Westchester County were still larvae but had stopped feeding. (Grubs eliminate all the undigested food from their bodies just before pupating, so they don't have that characteristic dark grey color on the "tip of the tail" and the overall body looks more yellowish.) So these grubs will be pupating soon, and adults should begin to emerge as early as late next week in Westchester County. Those of you in central or northern New England can expect an additional week or 10 days before the beetles begin to emerge.

European chafer adults should be emerging very soon throughout the region. I saw an adult asiatic garden beetle on the side of my house a few days ago (may it rest in peace), and May beetles (Phyllophaga) were swarming in large numbers around the lights of my garage about a week ago.

So... we should be nearly done with grub feeding activity in most of New England, but here come the adults.

Oh ... and I saw some sod webworm moths flitting about on my own lawn earlier this week as well. And chinchbugs are becoming active in Ohio, so we can expect an increase in their activity here very soon.

With all that lovely news, have a great week-end!

Submitted by: Dr. Pat Vittum

DISCLAIMER - As always, it is the responsibility of the applicator to verify the registration status of any pesticide BEFORE applying it. Different states have different regulations as well. The author and the University of Massachusetts are not liable for any consequences of any pesticide "recommendations". Mention of any trade name is not to be considered endorsement of a product.

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