Bean, lima-Lima bean pod borer

Etlella zinckenella

Pest description and crop damage The adult is a small brownish-gray moth with distinctive forward-protruding mouthparts and a broad white band on the leading edge of the wings. Eggs are tiny, white at first, turning pink, then gray. They are laid singly or in small clumps. Larvae are tiny and white at first, growing to up to 0.62 inch when mature and turning pink or tan. Larvae wriggle violently when disturbed. The pupa is up to 0.75 inch in a cocoon with soil particles adhering to it. Larvae bore through lima bean pods and eat the seed. It is seldom a pest of snap beans. Silk and droppings can contaminate pods, causing rejection from processors. Bush lima beans in the Columbia Basin have been injured seriously in recent years. Wild lupine seems to be a reservoir of infestation.

Biology and life history In California, overwintering larvae enter diapause in the fall, and pupate during winter. Adults emerge starting in March. The first generation feeds on wild lupines. There may be five generations each year. The complete life cycle takes at least 60 days, sometimes much longer.

Pest monitoring There is a sex pheromone that can be used for trapping.

Management-cultural control

Fall plowing to at least 8 inches deep can help destroy overwintering populations. Early year planting can help the crop achieve maturity before pod borers attain high densities. Crop rotation also is recommended where lima bean pod borers are a problem.

Management-chemical control: HOME USE

  • carbaryl

Management-chemical control: COMMERCIAL USE

Insecticides used for corn earworm also control this insect.

  • carbaryl (Sevin) at 1.5 lb ai/a. PHI 3 days for harvest of succulents, 21 days for harvest of dried, 14 days for forage, and 21 days for hay. REI 12 hr. Do not exceed 6 lb ai/a per crop. Toxic in aquatic habitats. Do not apply carbaryl dust to blooming weeds because of severe hazard to pollinating bees. Latex-based formulations, such as Sevin XLR Plus, are less hazardous to bees.