Screwworm Fly Larvae: Parasites of Mammals Including Humans

Cochliomyia is the scientific name of screwworm fly. Its larva is a parasite of warm-blooded mammals, including humans. These insects prefer hot and humid climates and cannot survive in cold and frost-prone areas. The larvae produce myiasis and feed on living tissue. This feeding causes deep lesions in the skin, which can be very damaging to the animal or human host.

The larvae are commonly called screwworn because they possess small spines on each body segment that resemble a screw’s threads. After the larvae hatch from the eggs they will dive head first into whatever food source, and burrow deeper perpendicular to the skin surface eating into live flesh, again resembling a screw being driven into an object. The larvae will then continue to feed on the wound fluids and the animal’s tissue. After 5–7 days, the larvae grow and depart from the wound to burrow into the soil and pupate. The pupal period varies from a week to upwards of 2 months, depending on the soil temperature. Adults breed only once during their lifetime, which is close to 20 days




Screwworm fly can be found in tropical countries like Southeast Asia, India, Papua New Guinea,   Africa and India.

The latest news involves a British woman who was found to have been hosting larvae of screwworms inside her ear. It was reported that she was infected after a swarm of flies pestered her while hiking in Peru; unknowingly, one flew into her ear. She reportedly started experiencing headaches and unbearable pains down the side of her face and an unexplained discharge from one ear and complained of the scratching sounds she continued hearing in her head.

Her surgeons finally succeeded in removing the mass of maggots from her ear.

screwworm larvae

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