If you've noticed several large gray flies buzzing against the windows of your Park Ridge home, especially in one room, you may be dealing with flesh flies. They're bigger than house flies, they have a distinct striped and checkered look and they're tied to decaying material. That last part matters most. A sudden group of flesh flies indoors usually means something has died nearby, often a rodent or bird inside a wall, ceiling or chimney. Below, we'll cover how to identify flesh flies, what draws them in and how to find the source. If the flies keep coming, our fly control services start with tracking down where they're breeding.
What Flesh Flies Are
Flesh flies are a group of flies that feed and breed on decaying animal matter, garbage and similar material. You'll usually see the adults first.
- Size. Larger than a house fly, often noticeably so.
- Thorax. Gray with three dark lengthwise stripes on the back.
- Abdomen. A gray and black checkerboard pattern that seems to shift as the light hits it.
- Eyes. Often reddish.
- Not shiny. Unlike blow flies, flesh flies aren't metallic green or blue.
One unusual trait: many flesh flies don't lay eggs. The female deposits tiny live larvae directly onto the food source, which gives the young a head start. The larvae feed, then crawl away to a dry spot to pupate before emerging as adults. In warm weather, the whole cycle can move quickly, which is why a few flies can turn into many within a week or two.
Signs You Have Flesh Flies
- Large gray flies at windows. Flesh flies are drawn to light and often gather at windows in one area of the house.
- Several flies at once. A group showing up over a day or two, rather than one fly that slipped in.
- A bad smell. A sweet, rotten odor coming from a wall, ceiling, attic, crawl space or chimney.
- Maggots or pupae. Larvae crawling along baseboards or small brown, seed-like pupal cases on the floor.
- Stains. Discolored spots on a ceiling or wall near the odor.
Flesh flies are often confused with blow flies, which also breed in decaying material but are shiny and metallic. Our guide on blow flies in the house covers those.
What Draws Flesh Flies In
Flesh flies follow the smell of decay. Indoors, the most frequent source is a dead animal in a hidden space. Mice, rats, squirrels, birds and bats can die in walls, attics, crawl spaces and chimneys, sometimes after getting trapped or after eating rodent bait. Other sources include:
- Garbage cans or bins that aren't emptied often.
- Pet waste in the yard or a forgotten litter box.
- Spoiled meat or food left in a garage freezer that lost power.
- Dead animals under decks or sheds outside.
Are Flesh Flies Harmful?
Flesh flies don't bite or sting. The concern is hygiene. Because they breed in carrion and waste, they can carry bacteria on their bodies and legs to surfaces and food. Keep food covered, clean surfaces where flies have landed and remove the source as soon as you find it. If you have health concerns, talk to your doctor.
Flesh flies are also a signal. If they're coming from a dead animal in a wall, that animal got into your home somehow. Without finding and fixing the entry point, it can happen again.
How To Get Rid Of Flesh Flies
- Follow your nose. Check where the odor is strongest and where flies are gathering.
- Remove the source. Wear gloves, bag the dead animal or spoiled material and put it in an outdoor trash can with a tight lid.
- Clean the area. Clean and disinfect the spot and remove any soiled insulation or nesting material you can reach.
- Clear the adults. Use a fly swatter or vacuum for the flies already inside. Once the source is gone, new flies stop appearing.
- Manage trash. Keep garbage bagged and bins clean, closed and emptied regularly.
- Seal entry points. Fix the gaps that let rodents, birds or other animals inside.
When the source is behind a wall, you may not be able to reach it. In that case, the odor and flies usually fade over a few weeks as the remains dry out. Our article on dead rodent smell in walls explains what to expect.
When To Call A Professional
Call for help if you can't find the source, if flies keep returning or if you suspect rodents or other animals are getting into your home. Our NJ DEP-licensed technicians can track down where flies are breeding, look for the entry points animals are using and recommend a plan using Integrated Pest Management and EPA-registered, eco-safe products. We offer free inspections and same-day or next-day service.
A cluster of big gray flies is your home's way of telling you something is wrong. Finding the source quickly is the best way to clear them out of your Park Ridge home.