The granary weevil, Sitophilus granarius (Linnaeus) is a well known devastating stored grain pest in many parts of the world. Its transportation through commerce has enable this grain pest to colonize nearly all parts of the world. Sitophilus granarius is a blackish beetle but color can vary depending on the environmental conditions and the region of the world where it is found. It is small with about 3/6 of an inch in size. The granary weevil has an extended range of distribution, but it prefers more temperate regions. In the United States, it is mostly found in the northern states than in the southern part of the country. What make this weevil more dangerous to grain is that both the adults and larvae feed on the grains. They can infest a wide variety of grain. The typical lifetime of the granary weevil can be anywhere from 7 to 8 months if conditions are favorable. A single female can lay from 50 to 250 eggs in her lifetime. If you would like to get more information on this grain pest you can follow this
Morphology of the granary weevil
Sitophilus granarius is a small, blackish beetle that has a long , slender snout. This species can easily be confused with other stored grain weevils that share similar morphological characteristics. Other grain weevils such as the rice weevil and the maize weevil also have snouts similar to that of the granary weevil. This weevil possesses a pair of stout mandibles at the end of the snout. The size of the granary weevil is about…
How to distinguish the granary weevil from other grain weevils?
The granary weevil is has no wings under the wing covers. It is also important to note that the thorax is marked with longitudinal punctures. These two characteristics that enable the distinction of the granary weevil from the rice rice weevil, a similar grain weevil.
Bioecology of the granary weevil
As for all Coleopteran insects, the granary weevil undergo a holometabolous development with four different stages, including eggs, larvae, pupae and adults. The adults usually live for up to 7 to 8 months. Each female can lay between 5 to 25 eggs during her lifetime. Eggs are laid on grains kernels and covered with a gelatinous fluid to protect them. Under optimal environmental conditions, it takes about 4 weeks for the development from eggs to adult stage.