You Are Here: Management Updates 2000 Archive June 16, 2000

Date: June 16, 2000
Category: Insects
Subject: Hyperodes Weevils, White Grubs

ANNUAL BLUEGRASS WEEVILS are finally beginning to "pop" throughout the Northeast. We have been collecting samples from Westchester County, NY, and are finding everything from small larvae to large larvae to pupae. The development seems to be a little behind that of recent years, but now things are happening quite quickly. We think that the warm weather in late March and early April started some of the adults moving but then the cold weather set in and held back further development. Functionally that means that we had a much longer period than usual during which the females were laying eggs, and that means we will see lots of different stages of development from here through the end of the summer.

For golf course managers who are beginning to see weakened or wilting turf, take a look - see whether you have any ABW larvae chomping away in the thatch or the crown. If most of the insects are still in the larva stage (they look like grains of rice with brown heads), you can get SOME (not a lot) of relief with an application of a fast acting and mobile material like Dylox or Proxol. Keep in mind that ABW is not on the label of most formulations, so in some states such an application would not be legal. The various synthetic pyrethroids do NOT appear to be very effective against the larvae at this point. (We use pyrethroids to control adults before they have a chance to lay eggs in the spring.)

If most of the insects are already in the pupa stage (more diamond-shaped and all white), DO NOT APPLY ANY INSECTICIDES. The pupae will not feed or cause any further damage, and they are not susceptible to insecticides, so you must play a waiting game.

Based on our observations throughout the Northeast, my best guess is that golf course superintendents in most of Massachusetts should hold off treating for the second generation until the first week of July. Readers in southern Connecticut or the metropolitan area might go just a little earlier. As usual, the timing will butt up against the July 4th week-end. Good luck!

GRUBS - We have seen asiatic garden beetle and oriental beetle adults active, and have had reports of European chafer adults. It is too early to predict grub activity - if soil moistures remain high, species like the Japanese beetle will do very well, while if we have unusually dry conditions (like 1999), the European chafer will do well again. Those who are planning to use a slow acting and long lasting material (like Merit or Mach 2) can treat any time now for Japanese beetles. I would still encourage folks to hold off on those applications for another week or two if targeting oriental beetles or European chafers - those species are less vulnerable to the chemicals so timing is very important. Remember, as always, to WATER WATER WATER - but then again, so far, Mother Nature certainly is taking care of that!

- Submitted by: Dr. Pat Vittum