When should I call a professional for flies?

Greg Baumann, Pest Sherpa

Short answer: Call a professional for flies when you cannot find or remove the breeding source, when activity continues after thorough sanitation, when a hidden carcass or wall void is likely, or when the problem involves a business, rental, or multi-unit building that keeps reseeding adults.

Flies are a source problem first

Adult flies you see on windows are the easy part. The hard part is the material producing larvae: a dirty drain film, overripe fruit, garbage juices, animal waste, or something dead in a wall or attic. Sprays and swatters drop numbers for a day. Source removal drops them for good.

Identification still matters. Fruit flies, drain flies, house flies, and blow flies point to different sites. Our Fly Guide walks through those habits so you know what to inspect before you spend money.

Homeowner steps worth doing first

• Clean drains mechanically if drain flies are suspected.
• Discard rotting produce and rinse recycling.
• Seal trash cans and clean outdoor bins.
• Check for dead rodents or wildlife in rarely opened spaces if blow flies suddenly surge.
• Use sticky monitors to track whether sanitation is working.

Clear reasons to hire help

• You cleaned thoroughly and adults rebound within days.
• You suspect a carcass in a wall, crawl space, or chimney chase.
• The issue is in a restaurant, clinic, or apartment building with shared plumbing.
• You need documentation for a landlord, HOA, or health inspection.
• You want an inspection that maps breeding sites rather than a fog-only visit.

What to ask a company

Ask how they will identify the fly, what sanitation they expect from you, and how they will confirm the source is gone. Education-minded firms talk about drains, dumpsters, and exclusion, not only chemical names.

Commercial and rental settings

Shared dumpsters, floor drains, and unit turnovers reseeds fly problems even when one tenant cleans well. Professionals who map those shared sources save everyone repeated spray visits. Ask for photos of breeding sites and a sanitation punch list you can share with a landlord or manager.

Seasonal spikes

Warm, wet weeks boost breeding. A one-time cleanup after a holiday party may need a second pass midweek. Professionals can help prioritize sites when several drains and dumpsters compete for attention. Track counts with sticky cards so you know whether the plan is working.

Related guides

• Fly Guide
• Do fly sprays actually work?
• How to Hire a Pro

References

• University of Minnesota Extension: Flies
• UC IPM: Flies
• UF/IFAS: Drain Flies
• EPA: Safe Pest Control