Pest profile

Southern House Mosquito

Culex quinquefasciatus · Diptera: Culicidae[2]

The southern house mosquito bites at night across the South and is the main carrier of St. Louis encephalitis virus there.[1]

Southern house mosquito female, brown with a banded abdomen, laying a raft of eggs on water
Southern house mosquito female, brown with a banded abdomen, laying a raft of eggs on water. (c) Lek Khauv, some rights reserved (CC BY) — via iNaturalist, CC BY 4.0

How to identify it

  • It's a medium-sized brown mosquito; the abdomen has pale, narrow, rounded bands at the base of each segment.[1]
  • Eggs are laid in floating rafts of 100 or more, loosely cemented together.[1]

Look-alikes

Look-alikeHow to tell them apart
Northern house mosquitoIts close relative; the two interbreed in a broad zone between about 36 and 39 degrees north.[1]

Where it lives

In the U.S. it ranges from Virginia across the southern plains to southern California and north to southern Iowa; it's in all 67 Florida counties.[1]

US map: public records from 7 states since 1990 (GBIF).

Biology and life cycle

Females lay egg rafts at night on nutrient-rich standing water, from waste water to bird baths, old tires and other containers.[1]

Larvae need five to eight days to develop at warm temperatures, and one female can lay up to five rafts.[1]

Damage and signs

  • Females take blood at night from mammals and birds, biting opportunistically.[1]

Health risk

It transmits West Nile virus and is the principal vector of St. Louis encephalitis virus in the southern U.S.[1]

Control

Prevention

Wear long sleeves and insect repellent for nighttime outdoor activity.[1]

Sanitation

Change water in pet dishes often and in bird baths at least weekly, remove unneeded containers and old tires, and keep ditches flowing.[1]

Pesticides

Larvicides applied where larvae concentrate kill the most immature mosquitoes with the least pesticide.[1]

Common questions

When does the southern house mosquito bite?
At night; it's a nighttime-active, opportunistic blood feeder.[1]
Where does it breed around a home?
In standing water such as bird baths, pet dishes, old tires and other containers.[1]

Sources

  1. University of Florida IFAS Extension (Featured Creatures), “Southern House Mosquito, Culex quinquefasciatus (EENY-457).” edis.ifas.ufl.edu/publication/IN837 (accessed 2026-10-06)
  2. iNaturalist, “Culex quinquefasciatus taxon page (order and family).” www.inaturalist.org/taxa/155309 (accessed 2026-10-06)

Updated 2026-10-14. Built from sourced records. Spot an error? Tell us.