Issue 11, July 2, 2012
Masked chafer adults have been numerous throughout Illinois. They are one-half inch long, tan, stocky beetles with a black band across the head, giving them the name of masked chafers. They are also called June bugs. Two species occur throughout Illinois, the southern and northern masked chafers.
The adults hide in the thatch during the day, emerging in the evening to mate and lay eggs. These insects do not feed, so they run out of stored food and die after about two weeks. After mating, females tunnel into the soil to lay their eggs. The resulting larvae are some of the white grubs that cause severe turf damage in late summer and fall. Getting a rough idea of adult numbers helps one decide whether an insecticide treatment will be needed to prevent grub damage.
Masked chafer adult.
The two species are out at different hours of the night. Southern masked chafer is more active between 9 and 11 p.m., whereas northern masked chafer is more active from midnight to 4 a.m. Between 10:30 and 11:00 p.m. is a good time to check on their numbers, because some of each species will be active at that time. Shining a light, such as car headlights, across the turf will reveal them flying over the turf. They are also strongly attracted to lights at night, and can be monitored by checking porch and street lights. (Phil Nixon)