European Chafer is at the Root of Spring Grub Damage in Northern Indiana

Reports of spring white grub damage are relatively uncommon in most of the Midwest. However, the European chafer is a slightly different beast and seems to be more cold-hardy than other annual white grubs. This characteristic allows it to feed later into the fall and start feeding earlier in the spring compared to Japanese beetle and masked chafer grubs. It also tends to infest areas with no previous history of white grub damage, including low maintenance areas. Folks in Michigan have been dealing with insect for many years now, but it is relatively new to Indiana; with the adults of this species first being detected in Porter, Kosciusko and Allen counties during 2007. We have now linked recent reports of spring white grub damage in LaGrange and Noble counties to this insect meaning that populations are well established in these areas and are likely established throughout the northern third of the state. Spring grub control is difficult to achieve and the only realistic chemical options are trichlorfon or carbaryl. Even then, repeated application may be necessary. If you notice white grub damage this time of year, take a closer look and try to find the larvae in the soil.

European chafer larvae can easily be identified using a 10X hand lens to inspect the raster pattern (shown above). Once established these insects may require some special attention going forward as they tend to be more damaging and somewhat less susceptible to traditional insecticide treatments. The best control is achieved using a preventive approach with applications of imidacloprid, thiamethoxam, clothianidin or chlorantraniliprole applied June through mid-July. Keep records of any European chafer infestation so you can identify areas to watch down the road.

Doug Richmond, Turf Entomologist