Billbugs
(crown & thatch inhabitant)
Adult billbugs are about 1/5" — 3/4" long. They are beetles with long snouts, or bills,
that carry to the tip a pair of strong jaws or mandibles with which the beetles chew their
food. Clay yellow to reddish brown to jet black in color. The beetles burrow in the grass stems
near the surface of the soil and also feed on the leaves. Several species of billbugs damage
lawns. The bluegrass billbug is a bluegrass pest. The Hunting Billbug causes damage to Zoysia
grass.
Bill Bugs are found in two forms: adult and larvae (infant). The adult Bill Bugs look like
a small beetle and are distinguishable by the long elephant-like bill that protrudes from their
head. Hence the name. The adult Bill Bug feeds on grass stems above the surface. The younger
Bill Bugs, or larvae, look like C-shaped, legless, wet pieces of white-rice and feed on grass
roots.
Bill bugs cause the most damage when they are larvae, and can spread and destroy large
sections of grass if not contained or killed.
Common signs of Bill Bug problems
are dead spots on your lawn that don't recover from watering. Since the larvae feeds on the
roots,
you can also tell by pulling-up on the dead grass and see if it comes up easily from the
roots. If so, it could be Bill Bugs.
Control Strategies
Billbugs are some of the most difficult turfgrass insects to control
because the adults' armor-like bodies do not readily absorb
insecticides. They also do not ingest much insecticide when they
penetrate a grass stem while feeding. The larvae are also difficult
to control because they are boring inside grass stems for much of
their lives. Bluegrass billbugs seem to cluster in neighborhoods,
especially where intensive bluegrass management is occurring.
Cultural Controls: Neighborhoods with mixed-grass lawns or lawns established using
resistant varieties are often less severely attacked. Wise turf
managers take time to observe all the turf in an area and watch for
the beginnings of billbug attack in a neighborhood. Although
bluegrass billbugs rarely fly, they may rapidly spread through
continuous lawns of a neighborhood.
Varieties of turf resistant to billbug damage are available and should be considered when
establishing a new lawn in an area with a history of billbug problems. Maintaining constant
soil moisture and moderate fertility levels during the fall months into winter helps mask damage
by low-moderate infestations.
Biological Control - Fungal Diseases - Billbug adults and larvae seem susceptible to
the entomophagous fungus, Beauveria. However, this fungus rarely attacks enough billbugs
to have a significant affect on the population. No commercial preparations of Beauveria are
currently available for use on billbugs.
Biological Control - Parasitic Nematodes - The entomophagous nematodes, Steinernema
carpocapsae, S. glaseri and several Heterorhabditis, have been used to
infect billbug larvae in the laboratory and in small field trials. These nematodes show promise
for the future but additional studies are needed to find the environmental conditions needed
for consistent results.
Chemical Control - Spring Adults - This is the most commonly used strategy.
Contact or stomach poisons are applied when adults come out of hibernation and are migrating
in search of sites to lay their eggs. Studies show that adults become active when the soil
surface temperature approaches 65 — 68 degrees F.
Repairing billbug damage
Billbugs attack
bluegrass lawns (and occasionally tall fescue and perennial ryegrass) in
June and feed on plant crowns and roots. If rainfall is adequate in late
June and July, lawns often recover from a billbug attack. If rains don't
occur, as happened this season, then we often attribute the browning to
heat and dry conditions and assume the lawn is dormant. If in fact areas of
the lawn are dead from a billbug infestation, renovation will be needed late this summer.
How do you know if the damage is drought related or actual billbug damage?
Do the "tug test" to determine if brown areas were killed by a billbug infestation.
Grab a handful of the brown grass and give a gentle tug. If the brown grass comes lose easily
and you find sawdust-like material at the base of the blades/stems, it's likely billbug injury.
If large areas are injured, it will need to be repaired in the fall via reseeding or resodding.
Threshold: 1 per sq. foot
