Sweetpotato Hornworm
Agrius cingulatus (Fabricius), Sphingidae, LEPIDOPTERA


DESCRIPTION

Adult - This grayish, heavy-bodied moth has a wingspan of 105 to 110 mm. The hind wings and abdomen bear bright pink bands.

Egg - Nearly spherical and about 1 mm in diameter, the translucent egg has a slightly greenish tint.

Larva - The first instar of the sweetpotato hornworm has a white body and a black anal horn. Later instars are basically green or brown with prominent, slanted black markings on each side of the body and a black anal horn. The head is also green or brown with 3 dark stripes on each side. A fifth instar hornworm may be 90 mm or more in length.

Pupa - The reddish-brown pupa is about 15 mm wide and 64 mm long. The large tongue case has a pitcher-handle-like appearance.


BIOLOGY

Distribution - Sweetpotato hornworms are common in tropical America and the southern U.S. Moths stray northward as far as Nova Scotia, but the larvae are too scarce to be pests that far north.

Host Plants - Sweetpotato and morning glory are the primary food plants of this hornworm although jimsonweed has also been reported as a host.

Damage - These large worms consume much foliage leaving only bare stems and petioles on plants. Sweetpotato hornworms have been reported to display armyworm-like habits in Florida; however, their movement in large groups has not been observed here in North Carolina. Larvae often hide under large leaves at the base of plants.

Life History - The biology of this pest is not well documented. Its life history is probably very similar to that of tomato and tobacco hornworms (see TOMATO: Hornworms). Moths appear in early June, again in August and September, and once more in early fall. There are probably 2-1/2 generations per year.


CONTROL

In small gardens, hornworms can be controlled simply by picking them off plants. Chemical control, however, may be necessary in commercial production. For recommendations, consult the current North Carolina Agricultural Chemicals Manual.

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