How to Get Rid of Blow Flies Infestation in Your House

Learn how to get rid of Blow flies and blow fly removal

Blow and Bottle flies are found worldwide, occurring in almost every place occupied by people. The name blowfly comes from the rotting animal carcasses' bloated condition that their larvae, known as maggots, infest. Blow flies are one of the most common flies found around dead animals.

These flies are common in populated areas and are often found near meat-processing plants, garbage dumps, and slaughterhouses.

Blow flies also include many species, including the common bluebottle fly, Calliphora vomitoria (Linnaeus), the green bottlefly, Phaenicia sericata (Meigen), etc.

Blow flies are slightly larger than true house flies, and the bodies of many are metallic blue or green. There are about 1200 species of blow flies worldwide, and in North America, there are 80. In many areas, including the American Southwest, blow flies are the most common type of flies found in and around buildings. Blow flies range from 7 to 16 mm (0.28 to 0.63 in); they have robust bodies and wide heads.

One of the first signs of a blowfly infestation occurs when the larvae leave the breeding medium to pupate. They are often found in decaying rodents that are located in walls, voids, or chimneys.

Get Rid Of and Prevent Blow Flies

1. Exclusion and Sanitation - To Remove Blow Fly Sources
  • Locate and eliminate all possible breeding sources. Blowflies and Bottle flies feed and breed on dead animals and garbage. Whenever possible, remove all material where the flies can lay their eggs. Killing adult flies will reduce infestation, but the elimination of breeding areas is necessary for proper management.
  • Proper sanitation measures must be taken with dumpsters and rodent control measures.
  • Exclude Blow/Bottle flies from a structure with proper screening and maintenance of doors and windows.
  • Garbage cans and dumpsters should have tight-fitting lids and be cleaned regularly.
  • Drainage will often aid control, getting rid of extra moisture.
  • Openings of buildings should be tightly screened.
2. Blow Fly Control (Insecticides and Fly Traps)
  • Blow/Bottle flies do not always require chemical control. However, if necessary, spray entry points on the building or fly resting areas with residual liquid insecticides, such as Cyzmic CS, Cyper WSP, or Bifen IT. To maintain residual control, and use these insecticides once a month.
  • Spray a ready-to-use spray, Invite Kill Zone over an area such as a dumpster to set up a "kill zone," then spray it with the recommended encapsulated Avesta CS. They will be attracted to the surface's kill zone and land on the sprayed surface
  • Fly Glue Traps such as Musca Stick - 12", Musca-Stik - 24", or Revenge Jumbo Fly Catchers may be used to trap and kill Blow flies. You can use the Gold sticks inside or outside. The Jumbo Fly Catchers are perfect for hanging in garages or basements. We carry a large assortment of fly glue traps.
  • Fly Baits are a common method of fly control, but not to control blow flies.
  • A pyrethrum aerosol will provide a contact kill for immediate relief. It may take a while for sanitation methods, residual chemical methods, and fly baits to begin working. Stryker 54, CB 80 Pyrethrin Aerosol, or PT 565 can be used as a contact, quick-kill insecticide.

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Biology and Habits

Blow flies, part of a large family of flies, is known for the larvae and immature flies infesting animal carcasses.

Adult blow flies feed primarily on flower nectar, plant sap, and other sugary materials. The female blowfly typically lays its eggs on the body of a recently killed animal. The eggs hatch quickly, and the larvae (maggots) then feed on the decaying tissues. In warm weather, some species can complete their larval growth within a week. They then burrow into the soil and pupate, to emerge later as adult flies. Blow flies play an essential role in nature by decomposing dead tissue in the wild.

  • Blow flies have played a role in medicine: species such as the green bottle fly and the black blowfly were once commonly used to clean open wounds in humans because the larvae tend to feed only on the decaying tissue. Since blow flies routinely move between dead animals or dung and human habitats, they may transmit disease organisms to people, including the bacteria that cause dysentery, typhus, and cholera.

Blow Fly Identification and Inspection


You can identify Blowflies by their metallic sheen. Black and green blow flies have a bluish-green color, and blue bottle flies have a metallic blue color. They range in sizes. The Black blow fly is about 1/4 inch, while the Bluebottle fly can measure 1/2 inch.

The maggots (cream-colored larvae) are 3/8 to 7/8 inch long and are legless and eyeless.

These flies have one pair of wings and sponging mouthparts. They taper from the larger round rear segment to a pointed head with a pair of mouth hooks.


Eggs are usually laid on meat or dead animals. Some blowfly species, such as the screwworm fly, lay their eggs on living animals.

Most of these flies found indoors originate from an outside source because of their breeding preferences. Garbage cans are a significant source for blowflies. Single cans have produced more than 30,000 flies in a week. If there are many blowflies inside, it most likely is a sign of a dead rodent or bird somewhere in the structure. Finding the animal or bird source is often difficult because it has been dead several weeks by the time the flies appear.

If a dead animal odor is present, the odor may help narrow the search area. Look for signs of dead rodents or birds that may have been living in walls or crawl spaces, or even living in lower cabinets and under major appliances. Fly larvae will crawl along a wall until they encounter a corner where they then pupate. Numerous pupae in a corner indicate the breeding source is near. If the flies are found inside the light covers in the ceiling, it means the flies emerged either in the ceiling or from the wall. The breeding source might be either in the ceiling or a wall.

Outdoors, inspect the area for dead animals; any nearby dumpsters or other garbage containers should be inspected.

Written by our resident pest control expert Ken Martin.

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