You Are Here: Management Updates 2007 Archive September 4, 2007

Date: September 4, 2007
Category: Insects
Subject: Chinchbugs, Billbugs, White Grubs, Sod Webworms

Miscellaneous thoughts on turf insects:

Chinchbugs - Some lawns have been showing telltale signs of drought stress throughout New England over the past few weeks. According to one of the Boston news stations, August 2007 was the second driest on record, so it is no surprise that things look a little parched! But now would be a good time to make sure that the areas that are looking drought-stressed are actually succumbing to drought and not chinchbugs.

Chinchbug damage often looks identical to drought stress. Take the time to look along the edges of the affected areas. Chinchbugs (a range of sizes from adults down through small nymphs) will be visible moving through the thatch, especially on a sunny day. Remember that the chinchbugs, if present, will move away from the dead grass and be feeding on grass that is still alive, so don't look in the centers of the brown patches!

In the most severe cases, it might be appropriate to apply a pyrethroid soon to knock out the chinchbugs that are active now and reduce the population going into the winter. Note that field trials conducted by Dave Shetlar at The Ohio State University indicate that permethrin is not very effective against chinchbugs but that most of the other pyrethroids, such as bifenthrin (Talstar™), lambda-cyhalothrin (Scimitar™), beta-cyfluthrin (Tempo Ultra™), and deltamethrin (DeltaGard™) all work quite well.

Billbugs can also cause damage at this time of year that looks like drought stress. The good news is that most of the billbug larvae should be done feeding very soon in New England, so the damage should not continue to worsen. For scouting, look for sawdust-like material in the thatch. This is the "frass" (insect poop) of the billbug and is very characteristic. Also if you tug grass blades at the base and they detach readily, look for evidence of feeding along the stems. Insecticides will not be very effective at this point, so just manage the damage as well as possible.

If you have properties that are experiencing chinchbugs or billbugs on a regular basis, you might consider renovating with grasses that contain endophytes. These grasses provide a natural protection against chinchbugs and billbugs, and are available in certain cultivars of perennial ryegrass and tall fescue. (Do not use Kentucky 31, a forage grass with endophytes removed!)

White grubs are beginning to show up now, especially in areas where the European chafer is the dominant species. The dry weather of August would favor the European chafers, and of course the roots are already stressed so  the damage may be even more apparent. For those of you who find high populations of grubs in the next week or two, you can get relief by applying trichlorfon (Dylox™) to the affected areas. Remember that you must water the areas thoroughly after application - and you might want to wait until we get a little rain to raise the soil moisture and draw the grubs back up closer to the surface.

Also remember that Dylox™ cannot be used on school grounds that are covered by the Children and Families Protection Act in Massachusetts.

Sod webworm moths are flying again right now. In fact I always get my annual reminder of this event when mowing my own lawn. The moths are flying in fairly high numbers - but that does not mean that you will see damage from the subsequent caterpillars. The species that are active in late summer lay eggs that become small caterpillars and overwinter in that stage. Because September should eventually bring some rain and cooler temperatures, the agronomic stresses will be diminishing and the turf should be able to withstand sod webworm activity without any insecticide applications.

So good luck with the potpourri of insects out there!

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. Trade names of materials are provided for informational purposes only and do not substitute for a thorough and careful reading of the label and application according to label instructions. 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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