Flies in a Los Angeles home or kitchen are a source problem, not a spray problem. Fruit flies point to fermenting residue, drain flies to the film inside a drain. House flies come in from trash and open doors, and a cloud of shiny blow flies usually means a dead animal in a wall. Remove the breeding material and the flies die off within weeks. In LA County restaurants, a fly infestation in a prep area suspends the permit.
Which fly do I have?
Identify the fly first, because each species breeds in a different place. Texas A&M AgriLife Extension puts it plainly: insecticides alone are rarely successful against indoor fly infestations.
- Fruit flies (vinegar flies). About 1/8 inch, usually red-eyed, hovering over fruit bowls, bar areas, recycling bins and the wet bottom of a trash can. They breed in fermenting fruit or vegetables, spilled drinks and unrinsed bottles and cans.
- Drain flies (moth flies). About 1/8 inch, dark and fuzzy, resting on walls near a drain and moving in short hops. They develop in the slimy film inside sink, shower and floor drains, grease traps and condensate pans.
- House flies. Under 3/8 inch with four dark stripes on the back. UC IPM notes that indoor flies have entered from outside in almost all cases, breeding in garbage, manure or lawn clippings.
- Blow flies. Shiny metallic green or blue, often with a copper tint, 1/4 to 7/16 inch long. A swarm in one room usually means a dead animal in the structure.
- Phorid flies. Fruit-fly sized, dark and humpbacked, running across counters before they fly. They breed in drains, garbage, flower vases, wet potted soil and soil under a leaking sewer line.
How do I find the breeding source?
Start where the adults are thickest, because small flies stay close to where they hatched. To test a drain, UC IPM recommends coating the inside of a cup with vegetable oil and inverting it over the opening for 24 hours. Emerging flies stick to the cup. Test every drain in the room.
Then check the hidden spots on the University of Kentucky's list: drain pans under refrigerators, rarely used toilets, clogged gutters and wet ground where an air conditioner drains.
What sanitation stops flies for good?
Remove the material the larvae eat, then keep it from coming back. Adult house flies live up to three weeks, so the infestation collapses once nothing new hatches.
- Trash. UC IPM advises plastic bags inside containers with tight-fitting lids, placed as far from the entrance as practical. Set cans out weekly even when they are not full, and wash them regularly with soap and water. In summer heat, house flies can go from egg to adult in as little as seven days.
- Drains. Scrub the film off the pipe walls with a hard bristle brush and drain cleaner, and clean the trap, where slime collects too. UC IPM says regular use of an enzymatic drain cleaner may help prevent the buildup. Boiling water and bleach give short-term control at best, and Kentucky's extension entomologists say not to pour insecticides down drains.
- Produce and bar areas. Refrigerate ripe fruit, empty recycling daily, rinse cans and bottles, wipe up spills under soda dispensers and bar mats, and let mops dry.
- Exclusion. Repair screens, seal cracks around windows and doors, and keep unscreened doors closed. UC IPM lists screens, doors and air curtains as the barriers that keep flies out.
Insecticides are a last resort. UC IPM says chemicals are only rarely required for fly management in homes, and a spray leaves the larvae untouched.
When is a fly problem really a rodent problem?
When large shiny flies appear suddenly and cluster at the windows of one room, a dead animal is usually inside the structure. Texas A&M notes that the adults appear one to two weeks after the maggots and emerge for one to three weeks. Remove the carcass when you can reach it, then seal the openings the animal used.
This is also why indoor rodent work should rely on traps, not poison: a rodent that dies inside a wall feeds a hatch you cannot reach. Our rodent control program traps and monitors, rodent exclusion seals the gaps, and exclusion versus baiting explains the trade-off.
What does a professional do that a can of spray cannot?
A professional names the species, traces the breeding site, treats it and documents what has to change. PesPro is QualityPro certified, holds California Structural Pest Control Board License #PR-6378, and our whole team works in English and Spanish.
Our restaurant pest control program includes dedicated fruit fly and drain fly programs aimed at the breeding film in drains and bar areas. Methods are food-safe and EPA-registered: gel baits, insect growth regulators, mechanical trapping and exclusion, with no broadcast spraying near food surfaces. Visits run before opening or after close, with a documented service log matched to what DPH inspectors check.
For a home, call and describe what you see; we will tell you whether it fits one of our programs. The written quote is free. Same-day service costs an extra fee and depends on the route; see how same-day pest control works. Fly work falls under the second tier of our 30-day guarantee: a return visit within 30 days costs 30% of the original price. The third visit at no extra cost applies only to cockroaches, bed bugs and rodents. Contact PesPro or call (323) 472-5329.
How do LA County health inspectors score flies?
The LA County Department of Public Health scores flies under item 24 of its Retail Food Inspection Guide, "No insects, rodents, birds, or animals present." A fly infestation is a major violation: numerous live flies, eggs, larvae or pupae in food preparation areas that could contaminate food, equipment, packaging or utensils. That finding suspends the permit and closes the facility for a minimum of 48 hours. A few flies in the delivery or prep area, or gnats and fruit flies anywhere in the facility, are minor violations.
Major violations deduct 4 points and minor violations 2. When a major violation suspends the permit, an additional 7 points come off, 11 in total. Gaps greater than 1/4 inch at doors and windows are marked separately under item 44, vermin proofing. On the county scale, 90 to 100 points earns an A, 80 to 89 a B and 70 to 79 a C. At 69 or below, the facility posts a score card instead of a grade.
After a vermin closure, the permit is reinstated only when the county verifies complete abatement and cleaning and sanitizing of all affected areas. The guide adds that professional pest control should be used to prevent a recurrence. If an inspector has already cited you, emergency remediation is available, with same-day service for an extra fee. For the full checklist, read health code compliance for restaurants.
Frequently asked questions
Why do fruit flies keep coming back after I throw out the fruit?
Because the fruit was only one source. Texas A&M's list of breeding sites includes unrinsed recycling, spills under soda dispensers and around bars, and floor drains. Damp mops and rags count, and so do bags of onions or potatoes in a pantry. Eggs already laid keep hatching for days after you clean. Dry out every fermenting spot and the population collapses once nothing new hatches.
Does bleach or boiling water kill drain flies?
Not for long. UC IPM calls it a common misconception: boiling water and bleach do not remove the organic film inside the drain, so they give short-term control at best. Scrub that film off with a hard bristle brush and drain cleaner, clean the trap, and use an enzymatic drain cleaner regularly. Never pour insecticides down a drain.
Does PesPro handle flies in homes, and what about mosquitoes?
Fruit fly and drain fly programs are part of our restaurant service. For a home, call and describe what you see; we will tell you whether it fits one of our programs, and the written quote is free. Our general pest control program covers ants, spiders and other common household insects. PesPro does not treat mosquitoes or termites; call your vector control district or a termite-specialty company instead.