Sitophilus zeamais Motsch

Family of Curculionidae, maize weevil (Sitophilus zeamais Motschulsky) is an important pest of maize in the tropics, particularly where grain is stored on-farm and without chemical protestants.

Pesticides for control of weevils are available, but the resource poor farmers of the developing world often cannot afford them. Sitophilus zeamais Motsch is virtually cosmopolitan throughout the warmer parts of the world, extending as far north as Joan and southern Europe.

Infestation often starts in the field, and is later carried into the grain stores; adults are winged and fly readily.

Eggs are deposited inside the grains, in small holes chewed by the female; each female may lay 300-400 eggs over a period of several weeks. The larvae remain inside the grains and pulpate when they reach a body length of about 4 mm.

The adults emerge through the characteristics small circular holes in the grains leaving a roughly circular hole approximately 1.5 mm in diameter, and are active insects, flying readily and often infecting ripe crops in the field.

The weevils use their elongated snouts, which have jaws for digging into the grain, while the females use their snouts for digging hole into which they lay eggs.
Sitophilus zeamais Motsch