|
Kentucky Bluegrass Billbug
LIFE CYCLE: The bluegrass billbug causes severe damage to
lawns throughout Northern Utah. The adult billbug is a hard-shelled
beetle about ¼ to ½ inch long. Its coloration is dull-gray
or gray-black. The beetle has a curved snout or bill (that gives
it its name) and has wings, but it rarely flies. (Baird and Hoffman*)
The billbug larva or grub, is white, legless, and c-shaped, and
is usually ¼ to ½ inch long with soft flesh. The pupa
is found in the soil and has an appearance similar to the adult
form but is soft and white in color and turns to the characteristic
black color as an adult. (Baird & Hoffman*)
The adult billbugs become active in the spring as the weather warms
up. They tend to feed on grass blades but do little damage to the
turf. The beetles start laying eggs from late April to June. The
larvae hatch and start to feed on the grass, progressing their way
to the crowns of the turf which is where damage occurs. The larvae
usually complete their feeding cycle by late July and begin their
pupil stage to become an adult.
The billbugs emerge from their pupil stage two to three weeks later.
After emerging, they continue to feed, as adults, on the grass until
the weather turns cold in the fall. They over-winter in a number
of locations including: under the soil surface in the turf, under
heavy leaf litter and many other protected sites.
DAMAGE: Adult billbugs do little damage to healthy bluegrass,
unlike the larvae or grubs. Feeding from early to mid-summer on
the stems and crowns of the plants, the grubs eventually work their
way to the roots, destroying the plants. Billbug damage is often
seen along the edges of driveways and streets first because the
cement warms the adjacent soil and the grubs prefer the warmer temperatures.
Later on in the year, the obvious sign that billbug grubs have been
feeding on a lawn is patchy brown spots in the sod, looking like
areas that have been drought stressed. These areas do not green
up when water is applied. Further investigation is needed after
seeing the brown spots. In these spots, the grass can be lifted
up like carpet due to the lack of roots, and grubs can often be
seen feeding under the damaged sod. Extensive damage to the sod
is indicative of a large population of billbugs that have built
up over a number of years.
CONTROL: There are a few strategies to controlling billbug.
At the present time, replacing susceptible varieties of bluegrass
with resistant varieties or using fescue or perennial ryegrass
sod is the only way to naturally control the billbug. Because
there are so few organic controls, pesticides are the simplest
way to control the bugs.
The best time to control the adult billbug is in the spring, between
late April and mid May. Any pesticide containing Merit® or
Mach2® offers the best control during this period.
If summer grub control is necessary, pesticides must be flushed
past the grass layer to the soil (heavy watering immediately after
application works best). Granular pesticides work better during
this period than liquids. One of the best granular bug killers
to use is Bayer® 24-hour grub control which contains Dylox®,
a powerful, but safe, pesticide. This chemical can also be found
in some other products. J&J Nursery carries a variety of products
to help control these and other garden pests. Please
call us or come in today.
*BAIRD and Hoffman: University of Colorado Fact Sheet on Billbug
Control
|
