Weevil Facts

Weevils are a type of very small beetle with distinctive characteristics. Throughout the entire world, approximately 60,000 different species of weevils are known to exist and are generally divided into true and primitive species. Most are not harmful to people or pets. They can, however, be devastating to agricultural crops and plants, as well as stored foods inside homes, stores, and warehouses.

  1. Visual Identification

    • Weevils are small in size, ranging from 4 millimeters to 16 millimeters in length. They may be oblong or pear-shaped, depending on the species, and may be black, brown, or a variation of colors. All true weevils have an elongated snout. True weevils have bent antennae, while primitive weevils have straight antennae. Like other beetles, weevils have two elytra, or wing covers, but not all weevils fly. The larvae look like small worms and may have light or dark heads.

    Development

    • The life cycle of the weevil occurs in four separate stages. Eggs hatch into larvae. The larvae form a pupa, and from the pupa, adult weevils emerge. The rate of development varies from species to species; but may spend as long a month in the larvae stage. Generally, the larvae do not have legs. It feeds off vegetation and other plant matter. The adults also feed on a variety of plants and plant products. Weevils are cold-blooded and rely on outside temperatures to warm their bodies. The rate of development and feeding habits are dependent upon the temperatures.

    Feeding and Infestation Signs

    • Typically, weevils eat a variety of vegetation. Weevils can be found in rice fields, cotton fields, and forests. They are also found in grain bins and dry food storage facilities. Weevils eat leaves, buds, roots, whole grains and grain flour. In agricultural and forestry areas, signs of infestations include small bored holes in the stems or trunks of plants and in the buds of flowering plants. The holes are bored by the female, as a place to deposit eggs and may be sealed over with a gelatinous secretion.

    Common Species

    • Boll weevils feed on cotton crops. Flour weevils, which are actually not weevils, but flour beetles, feed on the dust and flour of grains. Rice weevils feed on a variety of grains and bores into the kernels to feed and to lay eggs. The bean weevil is not a true weevil, but is a species of seed beetle. It feeds on and lays its eggs inside the bean pod and feeds on a variety of legumes. The wheat weevil is unable to fly and is commonly found in granaries or other dry food storage areas.