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Identification
Masked chafer adults are golden brown beetles, 3/4 inch (1.9
cm) long with dark brown heads. The adult beetle is hairy on the
underside of its thorax. Larvae are white, C-shaped grubs with dark
stripes on their backs and brown head capsules and legs. There is
also a characteristic pattern of bristles
on the underside of the posterior end of the abdomen. When full grown,
white grubs are about 1 inch (2.5 cm) long, much bigger than ataenius or billbug
grubs.
Hosts
All turfgrass species, especially annual
bluegrass (a common weed in turf), Kentucky
bluegrass, and perennial
ryegrass
Damage
Masked chafer grubs feed on the roots of turfgrass. Damage appears
in late summer or fall as irregular patches of brown, dying grass.
The ground often feels spongy, and the lawn can be rolled up if heavily
infested. Skunks, moles and birds may be attracted to lawns with
high grub populations.
Monitoring information
Dig around the roots in damaged areas—especially in late fall
through spring and look for whitish to yellow, wrinkled, C-shaped
grubs. Look for yellowish-brown adults in the early to mid summer.
Management
Aerating the lawn can kill significant portions of white grub populations
if they are feeding close to the soil surface. Follow recommended irrigation and fertilization
practices. A healthy lawn can tolerate some grub damage. If more
than 6 grubs are found per square foot, you may need to treat. Tiphiid
wasps are common parasites of masked chafers but may not provide
effective control. Beneficial nematodes may
be effective if applied when grubs are young. Other insecticides
are available including imidacloprid. Proper timing is essential.
Life cycle
For more information on lawn insects, refer to:
Pest Notes: Lawn Insects
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