[8] Within the United States’ regions of semiarid or arid climate, it has been historically identified as the primary transmission vector for malaria.

The head is covered in erect scales, dark-colored at the posterior, yellow-white at the center, and light at the vertex.

[4] Adults have a gray-brown prescutellar space and brown to black scutum, which possesses hairs of light yellow to golden-brown coloration.

[4] It typically remains west of the Rocky Mountains, but the mosquito has been observed slightly eastward in Texas, New Mexico, and southern Colorado.

[8] Adults typically reside in cool, shaded areas in the daytime, such as drainage tunnels, dark corners of homes, or beneath bridges.

[12] It belongs to the Angusticorn section, the Maculipennis group, and the Freeborni subgroup, which also includes the species A. hermsi, A. occidentalis, and A.

[citation needed] Flight patterns of A. freeborni remain in close proximity to breeding sites in the summertime.

[14][15] In contrast with other mosquitoes, Anopheles larvae are horizontally situated directly underneath the water surface.

[14] The adult A. freeborni gathers its strength on the water surface until it is able to fly away in search of a bloodmeal.

[14] Feeding is facilitated by oral brushes, which generate spiraling currents that direct microorganisms into the mouths of larval A.

[8] They commonly feed on humans and sizable domesticated animals, like cattle, horses, and dogs.

[18][6] Smaller-sized males will initiate a swarm to increase their chances of mating by decreasing competition, but also experience prolonged vulnerability to predators.

[19] The gonotrophic cycle indicates the time spent seeking out a host, feeding on a bloodmeal, egg development, and oviposition.

Female oviposition favors shallow, still bodies of water, which are at least partially sunlit during the day and which preferably contain some algae or other vegetative matter.

[4] Known predators include Erythemis collocata and Pantala hymenaea, species belonging to the Libellulidae family of dragonflies.

Predation partially overlaps with mating activity, as western malaria mosquitoes are most frequently attacked during swarming.

[21] Historically, A. freeborni has been considered the primary transmission vector for malaria in the western regions of the United States.

Such pesticidal agents as Bacillus thuringiensis, as well as some piperidine compounds and CIC-4, a lactone, are known to be effective at controlling A. freeborni larvae.

[22][23] In an effort to combat insecticide dependence, recent studies have investigated mosquitofish (G. affinis), a predator of the mosquito larvae, as a means of control.