Quick Facts...
- Many species of caterpillars attack Colorado Crops; the species
involved will affect control decisions. Use the following
descriptions to identify pests.
Fall Armyworm
Spodoptera frugiperda (Smith). This caterpillar is quite variable in color but has three
yellowish-white thin lines going down the back and a darker,
wider line and a broad yellowish line along the side. The setae
arise from prominent black tubercles. The most distinguishing
characteristic is the inverted white "Y" on the front of the head
capsule. This pest attacks a wide variety of Crops, particularly
corn and sorghum. It migrates from the south into Colorado every
year and is usually not a problem until the latter part of the
growing season.
Variegated Cutworm
Peridroma saucia (Hubner). This climbing cutworm is best distinguished by a row of
white to pale yellow dots that run along the midline of the back.
There are at least four of these dots and may be as many as one
per segment. The abdomen is mottled brown, sometimes with an
orange stripe laterally. This insect attacks a wide variety of
plants in Colorado, including alfalfa, corn, ornamentals and
various vegetable Crops. Three generations per year occur in
Colorado, starting in late May, with the most important damage
occuring in August.
Pale Western Cutworm
Agrotis orthogonia (Morrison). This subterranean cutworm has a greyish white, unmarked
abdomen. It is similar in appearance to the glassy cutworm but
has two distinct vertical brown bars on the front of the head
capsule. This is an early season pest that attacks small grains,
corn and alfalfa from very early spring through the end of June.
It has but one generation per year.
Glassy Cutworm
Crymodes devastator (Brace). This subterranean cutworm has an unmarked, uncolored,
somewhat translucent abdomen. It is similar in appearance to the
pale western cutworm but lacks vertical brown bars on the front
of the head. It is an early season pest of turf, corn, small
grains and alfalfa. It has one generation per year that is
completed by the end of June.
Western Bean Cutworm,
Loxagrotis albicosta (Smith). This small brown caterpillar is identified by faint diamond
markings on the back. Mature larvae are brown to pale grey with
dark brown bands behind the head. It prefers ear tips in corn
and developing pods in beans. This insect overwinters in
Colorado, although egg laying does not occur until late July.
Bronzed Cutworm
Nephelodes minians (Guenee). The abdomen of this subterranean cutworm is a dark bronzed-brown and has five distinct pale stripes running the entire
length. It will attack turf, small grains, corn and other
grasses early in the growing season. It has but one generation
per year.
Dingy Cutworm
Feltia ducens (Walker). This subterranean cutworm will occasionally behave as a
climbing cutworm. Its abdomen is a dull brown with a broad pale
stripe down the back. When full grown it is somewhat smaller
than the other cutworms with which it might be confused. It has
only one generation per year, attacking such plants as alfalfa,
corn, ornamentals and several vegetable Crops.
Darksided Cutworm
Euxoa messoria (Harris). This climbing cutworm has a greyish brown abdomen with a
narrow dark band on either side. It is an early-season pest that
has but one generation per year. It attacks a variety of Crops,
including several ornamental tree species.
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