Blowfly

Structure, Appearance and Characteristics

Adults:

• Adult varies from 8-12mm in length.
• Metallic green in colour.
• Regurgitating/Sucking mouthparts.
• Presence usually conspicuous because of larger size and loud buzzing sound.
• Attracted to light through windows.
• Most active in sunny conditions.
• Can travel a number of kilometres from original breeding site.

Life Cycle

Complete metamorphosis (egg – larva – pupa – adult). Population depends largely on seasonal and climactic conditions. Eggs or live larvae are laid in a suitable feeding medium. Preferred laying sites include animal carcases, meat and fish. Eggs can be laid in animal excrement and decaying human food wastes. Eggs laid in batches of 100-200. Eggs hatch within a day. Larvae (maggots) feed from 3-10 days. Larvae crawl away from feeding site to pupate in soil or some drier location. Adults emerge 5-10 days later. Typical life cycle takes 2-5 weeks.

Habitat

Anywhere near food sources, since the whole life cycle happens on or near the food source.

Food

Fresh or decaying vegetable matter, meats, all human foods.

Pest Status

Annoyance to humans. Because of frequenting animal excrement and human foods, they pose a serious threat to human health. Diseases spread include Salmonella, dysentery, typhoid fever, cholera, hepatitis, tuberculosis, poliomyelitis and parasitic worms. Cause problems with livestock, sometimes laying eggs or larvae in the crutch or wounds of livestock. Adults cause annoyance and spread of disease. Larvae have more nuisance value but become a real problem when active on livestock.

Control

Strengths include high reproductive capacity, very short life cycle, diverse food sources, strong fliers. A weakness is that they tend to rest at night which makes it possible for surface treatments to be used. Most controls involve hygiene, keeping potential breeding sites to a minimum around a premises. Reduction of breeding sites will dramatically reduce the population in a given location. If surface sprays are used, they should be applied where the flies are likely to rest during night or periods of inactivity. Because of their scavenging nature they are attracted to baits.