Gelechiidae

Adults are small, with a wing span of about 12 mm, and their wings are mottled gray and black. Hind wings are usually trapezoidal, pointed anteriorly, and the outer margin is sinuate. Caterpillars vary greatly in feeding habits; some are leaf miners, but many feed in rolled or spun-together leaves, or in stems or seed heads. There are some common species: Gnorimoschemagallaesolidaginis,which creates galls on the stems of goldenrod; the worldwide agricultural pest, pink bollworm, Pectinophora gossypiella; and the Angoumois grain moth. The potato tuber moth, Phthorimaea operculella, is a pest of stored potatoes, tobacco, tomato, and other Solanaceae. A related species, Scrobipalpopsis solanivora, damages stored tubers in Central America. There are several species thatare serious pests of forest trees.

Angoumois grain moth, Sitotroga cerealella (Fig. 11.1b; 11.2a) Adult wing span is 13-17 mm, and the body is grayish to yellowish brown; the hind wings are narrow, pointed, and densely fringed. Full-grown caterpillars are about 5 mm long, white with a yellowish brown head and small legs and prolegs; the pupa is reddish brown. The head has six ocelli arranged in a slightly curved line. Eggs are laid directly on the surface of grain; fecundity is 80-200 eggs. Hatching occurs in 10 days at 20 °C, in 6-7 days at25 °C, and 5-6 days at30 °C. Caterpillars penetrate grain kernels, and cover the entry hole with silk. Two or three caterpillars can develop in a single kernel of maize. From other grains, such as wheat, only one adult is produced.

Figure 11.2 Lepidoptera: Gelechiidae, Oecophoridae, Pyralidae, Tineidae. (a) Sitotroga cerealella (Gelechiidae); (b) Hofmannophila pseu-dospretella (Oecophoridae); (c) Endrosis sarcitrella (Oecophoridae); (d) Plodia interpunctella (Pyralidae); (e) Anagasta kuehniella (Pyralidae); (f) Tineola bisselliella (Tineidae); (g) Nemapogon granella (Tineidae).

Figure 11.2 Lepidoptera: Gelechiidae, Oecophoridae, Pyralidae, Tineidae. (a) Sitotroga cerealella (Gelechiidae); (b) Hofmannophila pseu-dospretella (Oecophoridae); (c) Endrosis sarcitrella (Oecophoridae); (d) Plodia interpunctella (Pyralidae); (e) Anagasta kuehniella (Pyralidae); (f) Tineola bisselliella (Tineidae); (g) Nemapogon granella (Tineidae).

Development is completed in about 21 days; although eggs hatch at 36 °C, but development is not completed above 34 °C. Minimum temperature for population increase is 16 °C; optimum relative humidity (RH) is 75-80%. The pupal stage lasts about 20 days at 20 °C, 10-12 days at 24-27 °C, and 8 days at 30 °C. Total development time at 70-90% RH is about30 days at 30 °Cand40 days at25 °C. There are four or five generations per year, but in heated buildings there may be 10-12 generations.

Caterpillars are a pest of stored whole grain or caked grain in containers, and they also infest grain in the field. Infestations occur in barley, rye, maize, oats, rice, and various seeds. The current distribution of this species is cosmopolitan, but it was first reported attacking grain in the French province of Angoumois. In the household habitat, ears of ornamental corn (Indian corn) may become infested, and also food and feed grain in storage. This insect is active at low temperatures and remains active during winter. It was introduced into North America before 1743.

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