The boll weevil, a small beetle, has historically posed a significant threat to cotton agriculture. Understanding its distinct appearance is important for identification. This insect primarily targets cotton plants, making identification crucial for those involved in cotton cultivation.
Overall Size and Color
Adult boll weevils are small insects, measuring between 3 to 13 millimeters (approximately 1/8 to 1/2 inch) in length. Their body shape is an elongated teardrop, wider in the middle and tapering towards both ends. The exterior is hard and shell-like, characteristic of beetles.
The coloration of a boll weevil can vary depending on its age. Younger adults may appear light yellowish, transitioning to a grayish-brown or reddish-brown as they mature. Older individuals can become dark red-brown, mahogany, or even nearly black. The body is often covered in plate-like scales or coarse yellow hairs, giving it a fuzzy or scaly texture.
Key Identification Features
A prominent feature of the boll weevil is its distinct, elongated snout. This slender snout curves downward and can be about half the length of the beetle’s body. Chewing mouthparts are located at the tip of this snout, used for feeding.
Elbowed antennae are another distinguishing characteristic, arising from the sides of the snout. These antennae have a long basal segment that fits into a groove on the snout, giving them a bent or “elbowed” appearance, with the end often appearing club-like. The boll weevil’s front legs also possess unique features; they have two small, stout spurs or double-pointed teeth on the inner surface of the upper joint, or femur.
The wing covers, known as elytra, protect the more delicate flying wings underneath. These elytra are often ribbed or grooved, contributing to its textured appearance. When resting, the two elytra meet along the middle of the back. The overall body texture may also appear hairy or scaly, especially on the sides and underside, giving the weevil a two-tone appearance with a darker top and lighter bottom.
Where to Observe Them
Boll weevils are primarily associated with cotton plants, as cotton is their sole food source and host plant. Observing them typically involves examining cotton fields and the plants themselves. Adult weevils can be found on various parts of the cotton plant, including leaves, stems, and especially the fruiting structures like cotton squares (flower buds) and bolls (fruit).
The presence of boll weevils is often indicated by their feeding activity. They drill holes into cotton squares and bolls, and females lay eggs within these structures. Infested cotton squares may turn yellow and drop from the plant; larger bolls might remain but become damaged or stunted. These visible signs of damage, along with the weevil’s physical appearance, help in locating them.