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Black Flies

May contain: insect, animal, apidae, invertebrate, bee, andrena, hornet, wasp, honey bee, asilidae, and fly

Nuisance biters. Do not transmit diseases in LA County

Often called “buffalo gnats” because of their distinctive humped back 

Black flies are small biting flies native to southern California and are a nuisance especially in foothill communities and areas where there is a constant flow of water.

They deliver a painful bite that affects both humans and domestic animals.

What you can do

  • Turn OFF water features, such as a fountain or man-made waterfall, for 24 hours once a week. This will deter and eliminate black fly development. Don't forget to turn it back on to prevent mosquitoes using the stagnant water.
  • If you are unable to properly maintain a water feature, remove it.
  • Wear repellent to stop the bites. It is impossible to eliminate every single black fly due to the ecosystem of the foothills.

What we do

Our agency monitors and controls known sources of black flies in rivers, streams, and any other areas that's accessible to our staff. New breeding sites can develop when a new source of running water is introduced, such as a fountain or man-made waterfull in a yard.

Black Fly Biology

Unlike mosquitoes, the aquatic larvae and pupae of black flies require moving water to survive and grow. Common breeding sites range from natural sources like rivers and streams to man-made water features like fountains and fish ponds.

May contain: water, nature, outdoors, river, and stream

Life cycle

1. The female deposits 200-500 fertilized eggs in or on flowing water.
2. Larvae emerge and attach themselves to rocks or foliage under the water and feed on organic debris that flow by.
3. In 7-10 days the larvae will pupate under water. 
4. Adults will emerge from the pupal case and float to the surface inside a bubble of air.

May contain: human and person