Blow Fly Maggot
Contact: Eric Day, Manager, Insect Identification Laboratory
August 1996
Blow Fly Maggot
Diptera: Calliphoridae, several species.
Size
3/8 to 3/4 inch (9.5-19.1mm)
Color
Pale
Description
Larvae are soft, worm-like, pale-colored insects.
Habitat
Large numbers of blow fly maggots may be seen crawling across
the floor, or numerous small, oval-shaped pupae may be found
under a rug close to a fireplace or wood stove when an animal
(bird, mouse, squirrel, etc.) has become trapped in the flue of a
fireplace or wood stove and died.
Life Cycle
Once the animal dies and its body begins to decay, blow flies are
attracted to it for egg laying. The maggots complete development
in the decaying flesh, then seek a dry place to pupate. Fly
maggots have the habit of wandering a distance before selecting a
place to pupate.
Type of Damage
They may wander into the living area of a house
and cause concern to homeowners.
Control
There is really no need for alarm or extensive control of these
insects. The pupae and larvae can be picked up and discarded.
The real concern should be for the cause of the problem. Check
the flue of your fireplace or wood stove. A blocked flue can
cause more damage than a few fly maggots or pupae on the floor.
Unused stoves and fireplaces may become nesting places for birds,
or a mouse, squirrel, or other animal may become trapped and die
in a flue stack and attract blow flies.