ovipositor is removed, with a waxy secretion that creates a plug. The plug quickly hardens, and leaves a small raised area on the seed surface. This provides the only visible evidence that the kernel is infested. Only one egg is laid inside each grain. When the egg hatches into a white, legless grub, it will remain inside and begin feeding on the grain. The larvae will pupate while inside, then chew a circular exit hole, and emerge as an adult beetle. A single female may lay 300 to 400 eggs during her lifetime. Adults can live for 5 to 8 months. Breeding conditions require temperatures between and 40% relative humidity. When the adults emerge, the females move to a high surface and release sex pheromones. Males are then attracted to this pheromone. Host range The maize weevil commonly attacks standing crops, in particular, maize before harvest, and is also commonly associated with rice. It infests raw or processed cereals such as wheat, oats, barley, sorghum, rye and buckwheat. It can breed in crops with a moisture content of a much wider range than S. oryzae, and has been found in fruit, such as apples during storage. Although the maize weevil cannot readily breed in finely processed grains, it can easily breed in products such as macaroni and noodles, and milled cereals that have been exposed to excessive moisture. Damage and detection Early detection of infestation is difficult. As S. zeamais larvae feed on the interior of individual grains, often leaving only the hulls, a flour-like grain dust, mixed with frass is evident. Infested grains contain holes through which adults have emerged. A possible indication of infestation is grain, when placed in water, floating to the surface. Ragged holes in individual grains, similar to damage caused by the rice weevil and granary weevil, may indicate infestation. In large stores of grain, an increase in temperature may be detected. The most obvious sign of infestation is the emergence of adults. One study recorded, 5 weeks after infestation, the emergence of 100 adults per kg per day. See also Granary weevil, also known as the wheat weevil (S. granarius) Rice weevil (S. oryzae) Home stored product entomology Invasive species List of common household pests Pest control References Further reading Proctor, D.L. 1971. An additional aedeagal character for distinguishing Sitophilus zeamais Motsch. from Sitophilus oryzae (L.) (Coleoptera: Cuculionidae). Journal of Stored Products Research, 6: