The black turfgrass ataenius is a small white grub that causes
sporadic, severe damage to golf courses in the cool-season turfgrass
zones. Fairways, approaches, tees, and greens may be infested.
Occurrence tends to be spotty, with only certain golf courses in a
vicinity affected. Damage to home lawns is uncommon.
The grubs commonly damage bentgrasses, annual bluegrass and Kentucky
bluegrass on golf courses, feeding on living plant roots as well as
decaying organic matter. The black turfgrass atenius is native to North
America where it occurs in all states east of the Rocky Mountains as
well as in California, Oregon and Washington. Damage to golf courses
occurs mainly in the north eastern segment of the United States, from
New England and the mid-Atlantic states and from Kentucky and Missouri
north to the Great Lakes, and along the Western Coast.
The black turfgrass ataenius has two generations per growing season
in Ohio and further south, and one generation in the Great Lakes
states, northern New York and New England. In the latitude of southern
Ohio, injury appears about mid-June and mid-August, coinciding with the
first and second annual broods of grubs. In more northern regions where
there is only one generation per year, damage shows up in July and
August. Adult black turfgrass ataenius are small, shiny black beetles
3/16 inch to 0.1 - 0.2 inch long and about half as wide, with distinct
longitudinal grooves on the wing covers. Newly emerged adults are
reddish brown but darken in a few days. Eggs are pearly white and tiny,
less than 1/32 inch. Newly hatched grubs are 1/10 inch long and hard to
see. Second instars are 3/16 inch and mature 3rd instars are 3/8 inch.
Mature black turfgrass ataenius grubs are often mistaken for young
grubs of Japanese beetles or masked chafers but the black turfgrass
ataenius grub has two distinctive, pad like structures at the tip of
the abdomen just in front of the anal slit. When mature, the grubs
burrow down 1/2-3 inches into the soil and excavate a cavity in which
to pupate. The pupae is small, about 3/16 inch long with the wings and
legs folded close to the body. Adults overwinter along the edges of
wooded roughs or in wood lots taking shelter under leaves, pine
needles, piles of grass clippings or other debris. In areas where two
generations occur each year, adults usually begin to emerge after
several warm days in late March through early May. Usually their
appearance coincides with the blooming of crocus and eastern redbud.
Egg-laying begins in early May and may continue through mid-June. The
beetles land on the turf and quickly burrow down. Clusters of 11-12
eggs are laid within small cavities near the soil-thatch interface.
Eggs hatch in about a week and the grubs take about 4 weeks to mature.
Damage caused by grub feeding or predators feeding on grubs
typically shows up in June. The second generation of adults emerges in
late June to early July. These adults mate and lay eggs in July and
early August, producing a second generation of grubs which damages turf
in late August and September. In northern regions, where only one
generation occurs, adults lay eggs in late June and damage occurs in
July and August. Injury appears as wilting and thinning of the turf,
despite adequate water. This is a result of stunted and damaged root
systems. While black turfgrass ataenius grubs are small they are often
found in concentrations of 200-300 grubs per square foot. Birds, skunks
and moles will tear up the turf to eat the grubs.