Screwworm Flies

Pronunciation

How to pronounce Cochliomyia: //ˌkoʊ.kli.oʊˈmaɪ.jə//

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Summary

Cochliomyia is a genus of blowflies known as New World screwworm flies, consisting of four species, including the primary and secondary screwworms, with significant veterinary and economic implications due to their larvae causing myiasis in warm-blooded hosts.

Physical Characteristics

Adult Cochliomyia flies have three body regions (head, thorax, abdomen), three pairs of legs, one pair of forewings, and one pair of halteres. They are generally metallic green to bluish green, with distinguishing features including orange gena and three black longitudinal stripes on the thorax.

Identification Tips

To identify Cochliomyia species, note the presence of bristles on the meron, coloration (C. macellaria has yellowish basicosta; C. hominivorax has brown), and larval characteristics such as the presence of pigmented tracheal trunks (C. hominivorax has them, C. macellaria does not).

Habitat

Primarily found in warm, tropical areas, including southern United States, Central America, and the Caribbean. Specific habitats include open wounds of vertebrates for oviposition.

Distribution

Cochliomyia macellaria is distributed throughout northern South America, Central America, the U.S., and southern Canada. Cochliomyia hominivorax was historically widespread but is now extirpated from the U.S. and Mexico due to eradication efforts.

Diet

Cochliomyia macellaria larvae feed on necrotic tissue (secondary screwworm), while Cochliomyia hominivorax larvae feed on living tissue (primary screwworm).

Life Cycle

Cochliomyia has a holometabolous life cycle consisting of egg, larva, pupa, and adult stages, typically lasting 21 days under optimal conditions, but can extend to three months in cooler climates.

Reproduction

Females lay 100 to 400 eggs once in a lifetime on open wounds. Male and female adults breed shortly after emergence, with females seeking wounds to obtain protein meals and lay eggs.

Ecosystem Role

Cochliomyia species play a role in decomposition processes as larvae feed on various tissues, including carrion and necrotic tissue.

Economic Impact

Cochliomyia hominivorax has a significant economic impact on livestock due to the damage caused by myiasis, leading to increased veterinary care costs and livestock losses.

Health Concerns

Both species can cause myiasis, with C. hominivorax being particularly problematic due to its ability to infest living tissue, leading to severe health issues for affected animals.

Misconceptions

Cochliomyia macellaria is often wrongly blamed for cases of myiasis that are actually caused by the more harmful C. hominivorax.

Tags

• Cochliomyia
• screwworms
• Diptera
• Calliphoridae
• livestock pests