This season continues to challenge our traditional thinking about insect seasonal ecology and management. Indiana and neighboring states are currently witnessing serious billbug infestations with late instar billbug larvae already present in the soil. This activity is easily 2-3 weeks ahead of normal. We advise all turf managers to take a close look at areas they suspect are displaying symptoms related to drought dormancy. Billbugs cause similar symptoms, but under these conditions they are capable of causing significant damage and loss of turf. Use the tug test to differentiate billbug damage from drought dormancy. Simply grasp a small group of suspect tillers (brown and dead looking) and pull straight up. If billbug damage is present, the tillers will break-off easily at or just below the soil surface and the bottom ends of some tillers may be packed with very fine sawdust like material (see Figure 1). This is diagnostic for billbug damage. Repeat this process at several locations across the damaged area.
At this time, management options for billbugs are limited to trichlorfon (Dylox), carbaryl (Sevin), or one of the faster-acting neonicotinyls; chlothianidin (Arena) or thiamethoxam (Meridian). Application of these materials should be followed by irrigation (1/4”) or rainfall to wash the applied material into the activity zone of billbug larvae. Over the long term, it may be advisable to renovate susceptible areas to endophyte-enhanced turfgrasses such as perennial ryegrass or tall fescue where agronomically feasible.
Doug Richmond and Tim Gibb
Turfgrass Research and Extension Entomologists