Quick Facts...
- Many species of caterpillars attack Colorado Crops; the species
involved will affect control decisions. Use the following
descriptions to identify pests.
European Corn Borer
Ostrinia nubilalis (Hubner). This caterpillar has a cream-to-grey colored abdomen with light brown spots. It is similar to southwestern corn borer, but during the summer months the latter has much darker spots on a whiter background. The European corn borer primarily attacks
field corn in Colorado and damages the leaves, stalks, shanks and
ears. It also can become a pest of sweet corn,
potatoes, sorghum, snap beans and peppers. Egg laying for the
first generation occurs during the first part of June. Second generation egg-laying can extend over a two- to four-week
period starting in late July.
Southwestern Corn Borer
Diatraea grandiosella (Dyar). During the growing season, this caterpillar has a white
abdomen with conspicuous dark brown or black spots. It is
similar in appearance to the European corn borer, but the latter
has lighter spots on a browner background. During the winter the
southwestern corn borer becomes pale yellow with very faint
spots. It is primarily a pest of corn but also attacks sorghum.
From one to three generations may occur per year in Colorado,
depending on the severity of the previous winter.
Beet Webworm
Loxostege sticticalis (L.). This is a small greenish black caterpillar with a narrow,
dark stripe running down the back and long setae that arise from
distinct dark circles. It is active when disturbed. This pest
will feed on the leaves of carrot, celery, pea, potato, spinach
and sugarbeet. Usually three generations of caterpillars occur
during the growing season, with the first appearing during June.
Alfalfa Webworm
Loxostege cerealis (Zeller). This is a small, greenish-black caterpillar with a broad
light stripe running down the back. It often will feed within
leaves that have been webbed together. These may be connected
to the ground by a silken tunnel through which it will retreat
rapidly when disturbed. It feeds on alfalfa, carrots, celery,
field corn and sugarbeets. The first of the two or three
generations of caterpillars occurs during May and June.
Bilobed Looper
Autographa biloba (Stephens). This is a greenish caterpillar that tapers from back to
front. It walks with a typical looping motion. It can be
distinguished from other loopers by a strong black line that runs
around the front of the head capsule. It will feed on alfalfa,
cabbage, lettuce and peas, but it rarely causes extensive damage.
One to two generations occur per year.
Celery Looper
Anagrapha falcifera (Kirby). This pale green caterpillar tapers from back to front. It
has a distinct white stripe on either side that contains a row of
white spiracles edged in black. The true legs are light green.
It walks with a typical looping motion. This pest prefers celery
but has attacked sugarbeets and lettuce. Two to three
generations per year of this pest occur in Colorado.
Alfalfa Looper
Autographa californica (Speyer). This greenish caterpillar tapers from back to front and has
a single white stripe on either side of the abdomen. The true
legs and part of the head usually are black. It walks with a
characteristic looping motion. It is similar in appearance to
the cabbage looper but lacks the reduced prolegs on the third and fourth abdominal segments and usually has dark thoracic legs and a dark
band on the side of the head. This looper will attack alfalfa
and sugarbeets as well as several horticultural Crops. Usually
two generations per year of this pest occur in Colorado.
Cabbage Looper
Trichoplusia ni (Hubner). This greenish caterpillar tapers from back to front and has
a distinct white stripe on either side of the abdomen except
immediately before pupation. It walks with a typical looping
motion. The reduced nipple-like prolegs on the third and fourth
segments of the abdomen help distinguish it from other looper
species. This pest will attack a wide variety of horticultural
Crops. Two to three generations occur per year in Colorado.
|
