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Facts About Blow Flies

The blow fly (Calliphoridae) bears a resemblance to the common house fly, but are slightly larger, and many of them have a metallic appearance. Among the filth flies in this group are the blue bottle fly, green bottle fly, and cluster fly. Blow flies share many of the feeding and breeding habits of house flies.

Blow flies are known to have a loud, distinct buzz, but they do not bite humans. Like most flies, they are known to wallow in filth and bacteria, and then spread it around with them wherever they go. 

What Does a Blow Fly Look Like?

Types of flies

Blow flies belong to the insect order Diptera. A common adult blow fly is usually a metallic black, blue, or green in color, and measures about 1/3" - 2/5" in length. Blow fly larvae are known as maggots, and look like tiny, pale-white worms.

Where Do Blow Flies Live?

Blow flies are found in all geographical areas of the world. Common habitats for blow flies include temperate to tropical areas with accessible layers of loose, damp soil and trash or other decaying material where larvae can develop and find nourishment. They thrive best in warm, humid weather.

Where Do Blow Flies Come From?

Blow flies typically breed outside and then make their way into homes. These pests come inside looking for food sources like rotting produce or decaying meat. If you’re seeing blow flies, it means that something nearby is attracting them. Blow flies may also enter homes in the fall looking for a warm place to spend the winter. In spring, they’ll become active and start popping up in homes.

Blow Fly Habits

Adult blow flies feed on a wide range of substances, including garbage, rotting vegetation, and other decaying materials, but the larvae of most blow fly species are scavengers that feed off of decaying animal carcasses or feces. Adult blow flies lay their eggs on dead animals for the larvae to feed on.

Female blow flies can lay up to 200 - 300 eggs on the flesh of a dead (or wounded) animal.  Larvae will hatch in as little as a few hours and up to a couple of days.

What Attracts Blow Flies?

Garbage, compost, animal feces, spoiled meat, any rotting materials, etc. can draw adult blow flies to your yard. Keeping problem spots cleaned up will go a long way to solving any blow fly problems. If your pet is harboring an open wound, he or she is vulnerable to having a wandering female blow fly lay eggs on them.

What Causes Blow Flies in the House?

Since blow flies are attracted to all kinds of organic and other rotting materials that aren't kept for long indoors, these flies are most often found outdoors. If you are seeing blow fly activity indoors, chances are there is something rotting nearby.

Are Blow Flies Dangerous?

As mentioned, blow flies do not bite humans, though they are significant carriers of bacteria and germs. These flies can be dangerous to animals, however, if they are able to fester in and lay eggs in a wound or sore an animal may be carrying. The feeding larvae exacerbate existing wounds, and can end up making the animal very sick, and may even cause the animal to die if left untreated. Female Blow flies may also lay eggs in an animal's eyes, ears, or nose.

The Blow Fly Life Cycle

Blow fly

As with most insects, the blow fly goes through a full metamorphosis (egg, larva, pupa, adult), though this particular fly species develops through three larval stages.

Once a female blow fly lays eggs in an animal carcass (she must consume protein first), wound, eyes, ears or nose, the first-stage larvae can hatch within 24 to 48 hours. Eggs are laid typically during the winter. Larvae develop through a second and third stage before pupating and then later emerging as adults.

The full blow fly life cycle can take two to three weeks from egg to adult to complete, and most adults live from two weeks to a month.

Will Blow Flies Eventually Go Away on Their Own?

If you have blow flies in your yard, they've likely been attracted to pet feces, decaying/rotting rodent carcasses, or other decaying organic material. If you are not regularly maintaining a clean and sanitary yard, garage, and outdoor area, Blow flies will likely continue breeding and increasing their populations (not to mention an increase in other pests, like ants and cockroaches).

Once blow flies have made it indoors in the fall, they will likely seek out-of-the-way areas to hide and overwinter. They will usually become active again on warm, sunny days, like cluster flies.  

If you are seeing a continuous blow fly presence in your home there's also a chance you may have a dead rodent in a wall void or crawl space, and the pests will likely not be leaving anytime soon until the carcass is removed.

How Do I Get Rid of Blow Flies?

How to Get Rid of Blow Flies Naturally

Sanitation is going to be your first and foremost defense against blow flies (and most other insect pests, like ants and cockroaches). 

  • Keep trash securely sealed, and remove daily. Remove animal waste in the yard regularly.  
  • Keep your sink free of dirty dishes, and keep countertops wiped down and clean.
  • Inspect and repair screens on doors and windows to prevent flies from coming inside.  

Pest Control Products

Pest control products would ideally not be used until all other methods have been implemented and you're still seeing a blow fly problem. 

Try an effective plant oil-based indoor fly killer for spot-treatment, like Maggie's Farm Home Bug Spray, or Maggie's Farm Flying Insect Killer. Plants don't like flies and other bugs any more than you do, and the natural oils they produce to protect themselves are amazingly effective at killing and repelling bugs of all sorts. For effective personal protection against flies (and mosquitoes), try plant oil-based Maggie's Farm Natural Insect Repellent.

For longer term, more thorough coverage, you can treat wider areas of your lawn with effective hose-end plant oil-based pest control products like Maggie's Farm Yard Bug Spray

Find more information here:

The Best Indoor Fly Killer Spray

Tips for a Bug-free Cookout

How to Use a Yard Bug Spray

How to Keep Pests Out of Your Lawn Naturally

How to Prevent Overwintering Pests


How do you control Blow flies in your home and yard? Leave us a comment! We want to hear your tips and tricks! 


For scientifically-tested, effective fly control in your home that is friendly to the environment, try Maggie’s Farm pest control products. Our promise is that our plant and mineral-based products are developed by scientists and seasoned pest control professionals to be the most effective.

1 comment

  • Thank you for the information on the Blow Fly. I do use Maggie’s Farm products, and they work wonderfully. That’s all I will buy. Thanks again!
    Julie Mcguigan

    Julie Mcguigan

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