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Adult beetles are shiny, jet black, 1/5 inch (0.5 cm) long, with
club-end antennae and parallel grooves on the wing covers. They may
be seen walking across turf. Larvae are very small, C-shaped grubs
with a scattered pattern of bristles on the last abdominal segment
and a pair of pads at the tip of the abdomen. These characteristics
help distinguish larvae from other
Annual bluegrass (a
common weed in turf), creeping
bentgrass, Kentucky bluegrass, perennial
Larvae feed on roots, causing irregular patches of brown or dead
turf. Damaged turf can appear drought stressed, and the problem may
be confused with damage due to turf root diseases such as summer
patch. Turf with extensive root damage can be easily peeled off
the soil. This pest is primarily a concern in golf courses, but occasionally
invades home lawns.
Look for ataenius grubs when you observe damage or about 2 weeks
after adults are seen. Dig around roots for very small, whitish,
C-shaped grubs up to 1/3 inch (0.8 cm) long with 6 legs and reddish
heads. Inspect outdoor lights around dawn for shiny black adults,
1/5 inch (0.5 cm) long. Dont confuse ataenius adults with similar
looking predaceous ground
beetles or Aphodius beetles.
Black turfgrass ataenius grubs cause damage mostly in turf that
is stressed by overwatering, high temperatures, heavy traffic, or
too-low mowing height. Improve root growth as much as possible to
allow turfgrass to withstand grub feeding by aerating,
raising your mowing height, and
following recommended irrigation
practices for your turf species. If you find more than 40 grubs
per square foot, you may need to treat with an insecticide. Beneficial
nematodes are effective when grubs are active.
For more information on lawn insects, refer to:
Pest Notes: Lawn Insects.