Beginner

Scientific Name
Spodoptera frugiperda

Identification
Full-grown fall armyworms are 4 cm long, varying in colour from light tan or green to near-black. Three white, thin strips run down the back. One thicker, yellow band with red spots runs along the side, just above the legs of the larvae.

Fall armyworm larvae have an inverted "Y" on their dark head and have similar stripes to true armyworm.

Often Confused with
True armyworm

Period of Activity
August

Scouting Notes
When populations are very high, fall armyworms may migrate from cereals to adjoining potato fields.   Carefully monitor border rows close to cereal fields

Thresholds
No thresholds are established.

Management Notes
Spot applications of a registered insecticide may be necessary if border rows are heavily damaged.

Advanced

Scientific Name
Spodoptera frugiperda

Identification
Full-grown fall armyworms are 4 cm long, varying in colour from light tan or green to near-black. Three white, thin strips run down the back. One thicker, yellow band with red spots runs along the side, just above the legs of the larvae.

Fall armyworm larvae have an inverted "Y" on their dark head and have similar stripes to true armyworm.

Often Confused with
True armyworm

Biology
Life stages
Eggs, larvae, pupae, adult moths.

The fall armyworm is an occasional pest of potatoes. In years when armyworm populations are high, they may feed on the potato crop.

This insect cannot over-winter in areas where the ground freezes.  Fall armyworm adult moths migrate from the southern U.S. and show up later in the season in Ontario, when the corn is fully grown.

Damage to potatoes results from the larvae feeding on leaves. Fall armyworm feeding occurs in the daytime, unlike true armyworm feeding, which occurs at night.

Host Plants - Corn, sorghum, and other plants of the grass family are the preferred hosts, but the fall armyworm also attacks alfalfa, bean, peanut, potato, sweet potato, turnip, spinach, tomato, cabbage, cucumber, cotton, tobacco, all grain crops, and clover.

Period of Activity
August

Scouting Notes
When populations are very high, fall armyworms may migrate from cereals to adjoining potato fields.   Carefully monitor border rows close to cereal fields

Thresholds
No thresholds are established.

Management Notes
Spot applications of a registered insecticide may be necessary if border rows are heavily damaged.