Pink Bollworm Facts & Information
Protect your home or business from pink bollworms by learning techniques for identification and control.
Behavior, Diet & Habits
Understanding Pink Bollworms
Adult pink bollworms are small and grayish-brown in color with folded wings and a slender body. Young larvae are small caterpillars with dark brown heads. Once the larvae have matured, they are about 12 mm in length with pink bands on their backs.
Pink bollworms are a major cotton pest in southwestern United States. Adult males and females feed on juices beneath the cotton leaves and are known to live up to two months. The pink bollworm larvae like to feed inside a growing cotton boll, hence their name. Feeding inside the cotton boll destroys the cotton. The pink bollworm prefers cotton, but will also feed on okra and hibiscus.
The pink bollworms prefer areas where cotton and orka are being produced. They originated in the eastern Indian Ocean region but have been introduced into Texas, New Mexico, Arizona, Nevada, California, Louisiana, parts of Arkansas and even in southern Florida.
Once laid, bollworm eggs take three to four days to hatch. They are white at first and become orange as they grow. Freshly hatched pink bollworm larvae are white with brown heads, turning pink in the fourth larval stage. Larvae bore into cotton plants to feed on their seeds. The larvae move from seed to seed in the boll, chewing the cotton as they move along. The larvae take twelve to fifteen days to develop, then they move to the soil to pupate. The brown pupa is immobile for its first seven to eight days.
Signs of Infestation
Common signs of an infestation include shedding of flower buds, deformation of flowers, reduction of lint development and destruction of the seeds in lint. Bollworms’ greatest harm is in the damage they do to cotton bolls. As the larva of the pink bollworm burrows into the boll, its stains the lint, rendering it commercially unusable. If the humidity is high, it only takes one or two larvae to completely destroy a boll.
When pink bollworm populations are high, they become very difficult to manage. Some successful defenses include the use of insecticides, timely crop termination, properly timed irrigations and compliance with plowdown requirements.
Experts in southern California have developed a reliable integrated pest management method to monitor bollworm populations. A sex attractant called gossyplure disrupts bollworms’ mating process, which can sometimes prove effective in reducing the number of overwintering bollworms.
Combinations of biological and chemical controls also have been successful. Using Trichogramma brasiliense with chemical insecticides has successfully controlled pink bollworm populations in India and the bacterium Bacillus thuringiensis has been effective in Egypt. More recently, nematodes have been used to control infestations.