Turf insect update from Danny Kline

July 13, 2010 in Extension

Last week I received several reports of green June beetle activity. I’ve also had some reports of May/June beetle activity. Current weather conditions are very conducive for many insect species. Billbugs, May/June beetle grubs, and green June beetles all prefer hot dry weather. Unfortunately, all of the preventive controls normally associated with white grub control are not very effective for green June beetle. Green June beetle larvae must be controlled later in the season, when the larvae are present. They can be controlled with curative applications of contact insecticides. These larva are usually present in great numbers in late August into September.

Here is some information from Paul Heller’s green June beetle fact sheet: “The most common method of controlling this insect is to rely on a late-summer through early fall curative application. Unfortunately, this treatment usually is completed after green June beetle grub damage is noticeable on home lawns, including the presence of tunnels and small mounds of soil located on the surface of the grass. These grubs are relatively easy to control at this time with an application of a contact insecticide; however, it is important to recognize that a late-summer/early fall application can result in dead grubs on the turf surface. Ideally, curative applications should be made late in the day since grubs move to the surface during the evening. These insects die at night on the surface rather than in soil burrows. Thus, you may end up with a large number of dead, smelly grubs on the surface of your grass. In some cases, you may need to remove the decaying dead grubs. Also, keep a history of the site infested with green June beetle grubs for a future reference guide. Thus, read the label carefully prior to making your selection”

Billbugs are a particular problem right now. The heat and drought conditions have allowed billbugs to develop quickly. I have observed adult activity in my pitfall traps over the last few days, which means we are soon going to have second generation eggs being laid in the soil. This second generation will produce damage in August, and will continue to cause damage into the fall, as long as it stays hot and dry.

Hot dry weather also helps sod webworm development. Adults have been observed flying at night, and I’ve had several adults in my black light trap. I have been closely monitoring a site in central PA that has a history of sod webworm problems. No larvae have been found yet, but this heat will push them to develop faster.