General Information

Common name: Cotton boll weevil
Scientific name: Anthonomus grandis
Coleoptera:Curculionidae

Synonyms: Boll weevil, Mexican cotton boll weevil (CABI, 2000)

Host plants

Cotton

Distribution

Africa, Europe, USA, Western Hemisphere

Damage

1. Feeding punctures on squares and bolls as results of adult's feeding damage. The boll weevil uses its small mandibles (located at the end of their snouts) to chew and feed into the inner portion of the boll.
2. A raised, pimple-like scar is found on the square or on the boll as a result of female depositing its egg on the feeding puncture and sealing it with a glue-like substance.
3. ' Flared square', is wherein bracts spread away from the floral bud, as a result of larval feeding.

Description

The eggs are small and ovate-shaped. These are deposited inside a square or boll. One square is one egg laying site, where the female lays only one egg. More eggs are found in 1 boll. Egg period is 3-5 days.

The larva is white C-shaped grub, legless, long, and wrinkled with light brown head and mouthparts. It is about 13 mm long.

The pupa is found inside the same square or boll where it develops. Pupa looks very similar to the adult but with soft skin. It pupates within the square that falls into the ground.

The emerging adult chews the square for its exit.

The newly emerged adult is reddish or pinkish, with not fully-hardened skin. It becomes grayish or brown and becoming nearly-black with age. Its body is hard-shelled and is sparsely covered with small light-colored hairs which are dense near the center of the thorax, creating an indistinct light-colored stripe (on the center of the thorax). It has an elongated snout (beak) which is true to all weevils but its most distinguishing feature is the 2 branched veins near the end of the front thigh, the inner one being much longer than the other. Boll weevil varies considerably in size, ranging in length from 3-8 mm. It has a great ability to travel from one field to another.