Black turfgrass ataenius

A small black scarab beetle (about 1/5 inch) whose damaging stage is a tiny white grub roughly half the size of common turf grubs, found in the upper soil and thatch feeding on roots. Confirm by examining the raster pattern and the small size of grubs, or by flushing/soil-sampling stressed areas. Predominantly a problem on golf courses, especially on bentgrass-ryegrass mixtures and annual bluegrass.

Irregular wilting and dead patches that look drought-stressed even when irrigated, because root feeding cuts off water uptake; heavily fed turf loses its root anchorage and can be lifted or rolled back like loose carpet. Damage often coincides with summer heat stress, compounding the injury.

The black turfgrass ataenius is a scarab beetle with complete metamorphosis. Adults overwinter in woodlots and leaf litter, fly into turf in May and June, and lay eggs in the thatch. Grubs feed on roots and crowns for about two months, with first-generation damage appearing by late July; they pupate and a second generation of adults emerges in August, producing late-summer grubs and new adults that return to overwintering sites in fall. Two generations per year are typical, more in warmer climates.

Damage occurs in summer, peaking in late July and again in late summer from the second brood, and is concentrated on highly maintained, heat-stressed cool-season golf turf (fairways, tees, greens, collars). Stress from close mowing, heavy traffic, and summer fertilization aggravates the visible decline.