Maize weevil (Sitophilus zeamais)

Pest type: Secondary pest, scavenger.

Distribution: Worldwide, especially temperate with poor hygiene. The mealworm beetle can maintain itself perfectly in our temperate climate.

Identification: Mealworm beetles are 12-18 mm long and black to reddish brown in color, parallel-sided. The appearance of the T. molitor is glossy and the T. obscurus is matt. The mealworm larvae (elateriform) are yellowish brown, have a length of 28mm and have three pairs of well-developed legs.

Similar species: Dermestes, Lophocateres, Alphitobius, Cynaeus.

Life cycle: Optimal conditions are 120 days at 25-27 ºC. The beetles convert approximately 400 sticky eggs on the breeding ground of the larvae. The larvae are mobile, and are external feeders. The larval stage lasts 1 to 1.5 years and overwinter as larvae. Adults are long-lived and feed on the commodity and can fly.

Commodities infested: These are products of both animal and plant origin, including old, humid flour residue. The larvae bores its self preferably into solids, such as flour and bakery food products as well as in rags. Sometimes the larvae live in rotten wood or insulation, drilling themselves corridors (not fresh, healthy wood) or making use of corridors bored by other insects. Dissemination of mealworm beetles often takes place from bird nests. Mealworm beetles cause damage in prolonged stored flour. Mealworm beetles may become a problem as massive food supplies, feed, etc. remain untouched lying under fairly humid conditions.

Good hygiene is important for prevention.

Treatment: Controlled Atmosphere for infestation in product
Treatment: Heat Treatment for infestation in buildings