Anopheles — the malaria mosquito
Anopheles spp.
Quick answer
Anopheles are the night-biting mosquitoes that transmit malaria. They rest with their body tilted at an angle (a field ID tell), breed in clean, slow or still natural water (marsh edges, ponds, swamps), and feed dusk-to-dawn. Malaria is not currently endemic in the U.S., but competent Anopheles vectors are present, so locally-acquired cases occasionally occur. They respond to CO₂, so a trap running through the night targets them.
Biology & identification
Recognizable by a distinctive resting posture — abdomen tilted up at roughly 45° from the surface — and, in many species, spotted wings. Unlike Culex, Anopheles prefer clean, unpolluted water with vegetation: the margins of marshes, swamps, ponds, ditches, and slow streams, where females lay eggs singly on the water surface.
U.S. species include An. quadrimaculatus in the East and An. freeborni in the West — both historically competent malaria vectors. Adults are typically strong fliers that can range further from breeding sites than container Aedes.
Peak activity — when it bites
Nocturnal — host-seeking runs from dusk through dawn, often with significant late-night and pre-dawn biting.
Many vector Anopheles are also endophilic and endophagic (entering structures to bite and rest), which historically made indoor bed nets effective against them.
Why it bites — host-seeking
Females need blood for eggs. Anopheles host-seek by CO₂, heat, and skin odor at night; many are strongly drawn to a warm-bodied host’s breath-and-skin signature.
Feeding preference ranges from human-preferring (the major Old-World malaria vectors) to more opportunistic in U.S. species.
How the CO₂ trap targets it
A reasonable trap target. Anopheles respond to CO₂ and heat and are active through the night, within the trap’s run window, so a CO₂ + heat trap draws host-seeking females.
Honest note: because some Anopheles are endophilic (bite and rest indoors) and range further from breeding water, outdoor yard trapping addresses the outdoor-active portion of the population.
Range & vector status
The genus that transmits malaria. Malaria is not currently endemic in the United States, but competent Anopheles remain widespread, so rare locally-transmitted cases occur when a vector bites an infected traveler and then others.
Stated factually — present competent vectors, not endemic disease — with no prevention claim.
Sources
- U.S. CDC, "Malaria — Anopheles mosquitoes."link pending verification
- Takken, W. & Knols, B.G.J. (1999), odor-mediated host attraction in Anopheles, Annual Review of Entomology 44:131–157.
- Kline, D.L., attractant enhancement of Anopheles trap catch.link pending verification
Common questions
Is malaria a risk in the United States?
Malaria is not currently endemic in the U.S., but competent Anopheles vectors remain widespread, so rare locally-transmitted cases occur when a vector bites an infected traveler and then bites others. This is a factual statement of vector status, not a disease-prevention claim.
How do you identify an Anopheles mosquito?
By its resting posture: the abdomen tilts up at about 45° from the surface, unlike the parallel posture of other mosquitoes. Many species also have spotted wings.
When are Anopheles mosquitoes active?
They are nocturnal, host-seeking from dusk through dawn with significant late-night and pre-dawn biting.