Green Bottle Fly (Lucilia spp.)

The green bottle fly is one of the most common and widley distributed flies in California. The adults are easily distinguished by their metallic green body. They are one of the first flies to lay eggs on recently cooked meats, fresh decaying garbage or dead animals. With high temperatures, the life cycle, from egg to adults, can be completed within 7 days or less. Larvae disperse from their food source to pupate and may be found climbing on walls near garbage cans and compost bins. They are active year-round in warmer regions of the state and populations peak during summer months.

Blue (Calliphora spp.) or Black Blow Fly (Phormia spp.)

Blue and black blow flies are related to the green bottle fly. The blue blow fly, also known as the common blow fly, proliferates in warmer months of the year and breeds in the carcasses of dead animals. The black blow fly is more abundant during cooler months and has larval sites similar to the green bottle fly, but takes longer to develop. Sometimes blue blow flies may breed indoors if there is a dead animal inside of a structure. If you are experiencing these flies in your home, inspect the basement, crawl spaces and attic for dead animals (rats, birds, raccoons, skunks, cats).

Vinegar/Fruit Fly (Drosophila spp.)

These small flies commonly fly around and land on walls in kitchen and bathroom areas, and floor drains. Larvae feed on anything that ferments such as ripe/rotten fruits, damp flour, residue in soda and beer cans, and potato skins. Locate and remove larval food sources to effectively eliminate the fly problem. Remove recycled cans and bottles regularly.

Drain Fly (Psychodidae)

Small flies with pointed “hairy-looking” wings. They rest on walls or ceilings of bathrooms or kitchens. This fly breeds in rich organic matter usually originating from a plumbing or sewage leak. Also breeds in slime accumulations in drains. Repair plumbing leaks and clean drains with a brush and enzymatic type drain cleaner to prevent drain fly outbreaks.

Lesser House Fly (Fannia spp.)

Swarms of flies hovering under porches, patios and other shaded areas are usually the lesser house fly. They often fly in an irregular back and forth pattern. Primary larval food sources are lawn clippings, compost, bird manure (roosting pigeons), or other moist organic sources. Pesticide applications to swarms or on walls around swarm site may give temporary control. Fly traps are not effective for this fly; the most effective tactic is to tightly cover or eliminate larval sources.

House Fly (Musca domesticus)

The house fly is one of the most common flies in the world. Larvae breed in landfill sites, rotting compost, and animal manure. Adult flies cease activity in the fall and seek overwintering sites where they remain inactive for the winter. These flies can also be found in rural areas with livestock and animal manure buildup. Elimination or treatment of larval sources is the best control method, but exclusion with screens on windows and doors may be the only solution.

Soldier Fly (Hermetia illucens)

This fly is commonly found in compost bins. Black solider fly larvae are commercially available for decomposing garden waste and other vegetation. Larvae play an important role in composting. The adult Soldier flies are quite large, and can be a nuisance in composting or recycling sites.

Stable Fly (Stomoxys calcitrans)

This robust black fly has a painful bite. The larvae feed in damp, highly organic materials such as moist hay and droppings. Occasionally this fly can become a problem in dairy farms and other rural settings with livestock.

Small Dung Fly(Sphaeroceridae)

This fly has similar habits to the Vinegar Fly. The larva feeds in organic material usually due to plumbing and sewage leaks as well as decaying vegetation and rotten fruits.

Black Valley Gnat(Leptoconops torrens)

This is a very small “no-see-um” gnat that has a very painful bite. It breeds in a specific soil type found in and around the Pleasanton area of the county. Due to the development of new housing in this area, this fly is rarely encountered.

Fungus Gnat

The non-biting fungus gnat breeds in over-watered plant soils and may become a nuisance. Replacing potted soil or drying out soil will help reduce numbers.

Cluster Fly (Pollenia rudis) & Face Fly (Musca autumalis

Some flies will overwinter in large numbers in homes; usually in attic or wall voids. Many flies may enter the living area and cause a considerable nuisance. The Cluster Fly (Pollenia rudis) which feeds on earthworms will utilize homes to overwinter. The Face Fly (Musca autumalis) which is similar in appearance to the House fly will also overwinter within homes. Pesticide applications can be used to kill existing flies for temporary control. Sealing all exterior cracks and openings is highly recommended for preventing future infestations.

If you have difficulties finding the larval food source or identifying a fly, call our District (510-567-6800) or submit an online request for service. We will inspect your property, identify the fly and make recommendations for the elimination of the larval food source.

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Common Flies in Alameda County

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