Oriental Latrine Fly (Chrysomya megacephala) — identification, habitat & look-alikes

The oriental latrine fly is a metallic blue-green blow fly with a big head and large red eyes, common around garbage, latrines, and fish in warm weather. Native to warm parts of Asia and Australasia, it has spread since the 1970s to Africa and the Americas, reached the US in the early 1990s, and is still expanding its range here. It's one of the first flies to arrive at a dead body, which makes it an important clue for forensic investigators. It's also called the oriental blue fly.

Appearance

Appearance: About 1/3 in (8–10 mm) long, with a shiny blue-green thorax and abdomen, a large head, and red eyes. In males the eyes almost touch; in females they are set apart.

Look-alikes

Hairy maggot blow flyChrysomya rufifacies

Look at the breathing hole () on the front of the thorax: it's pale or white in the hairy maggot blow fly but dark brown or dark orange in the oriental latrine fly. You'll need a close-up photo to see it.

Why they get mixed upBoth are metallic blue-green Chrysomya flies that have spread in the US and share the same carcasses.

Common green bottle flyLucilia sericata

The green bottle fly is a little smaller (5–9 mm) and more golden green, and males have eyes set slightly apart instead of nearly touching.

Why they get mixed upBoth are shiny green blow flies found around garbage and carrion.

Where it lives

Typical habitats: Towns and cities
Garbage and latrines
Fish markets and fish-drying areas
Range: In the US it has been recorded in Florida (1992), California, Texas, Louisiana, Hawaii, Indiana (2012), and Tennessee, and it is still expanding its range. It likely arrived through ports and airports.
Preferred conditions: Loves warm weather and lives close to people. It's common when it's hot and scarce when it's cold.

Behavior

Diet: Adults feed on feces, sweet substances, and especially fish. Larvae (maggots) grow in rotting meat, fish, and feces.

Life cycle

Reproduction: A female lays about 200–300 eggs on carrion, fish, or feces, often within hours of finding a fresh carcass.
Larva: In warm conditions it goes from egg to adult in about 10 days (at 81°F/27°C). Full-grown maggots are about 5/8 in (16 mm) long.

Conservation

IUCN Red List: NENot EvaluatedNot yet assessed
Threats: It can carry germs and parasite eggs from feces to food, including antibiotic-resistant bacteria. Maggots occasionally infest open wounds () in people and animals.