White Grub Prediction


Dave Shetlar reported that he is predicting a "good year" for white grubs in many areas of Ohio.  His prognostication is based on several observations.  First, as reported in BYGL 2013-13 (06/27/13), localized JAPANESE BEETLE (Popillia japonica) populations have been very heavy in some areas of the state, particularly in southern and northeastern Ohio.  Dave noted that in some cases, the actual beetle population densities may be underestimated with adults spending an inordinate amount of time being less visible as they mate and lay eggs rather than feeding on plants where they are more easily observed. 

Second, adult populations of both the NORTHERN MASKED CHAFER (Cyclocephala borealis) and the SOUTHERN MASKED CHAFER (C. lurida), two of our other common "white grub producing" beetles, have been very high this season, particularly in the central and southern parts of Ohio.  Indeed, Joe Boggs reported that an inordinate number of northern chafers came to his porch lights earlier in the season followed now by an equally dramatic number of southern chafers.  The onslaught from both beetles has made evening porch sitting a challenging endeavor!

Finally, soil moisture has remained high throughout the state, and has almost constantly been recharged.  Both Japanese beetles and the masked chafers lay dehydrated eggs that must absorb water from the soil in order to develop, so wet soil conditions support a greater egg hatch which means more white grubs.  Time has just about run out for applying one of the standard grub control products such as imidacloprid (e.g. Merit), thiamethoxam (e.g. Meridian, Maxide), clothianidin (e.g. Arena), or chlorantraniliprole (e.g. Acelepryn).  However, dinotefuran (e.g. Zylam) remains a viable option since the recommended timing for applying this insecticide for white grub control is early August.