PHONE
800-231-3236 (toll free)
707-285-2200 (office)
707-285-2210 (fax)

ADDRESS
595 Helman Lane
Cotati, California
94931-9736

HOURS
Monday through Friday
7:00AM to 3:30PM

6. WESTERN MALARIA MOSQUITO (ANOPHELES FREEBORNI)

Anopheles freeborni is the most important malaria vector in California. In our lifetime, endemic malaria has been eradicated from the U.S. But in our grandparents time, it was so serious that education guidelines called for it to be included in the instructional program in every primary school. Today, carrier mosquitoes still occur throughout the state, and hundreds of active infections are discovered every year in tourists and immigrants from other countries.

Anopheles are easily distinguished from other mosquitoes: their eggs are laid singly and have small floats on each side; the larvae lack the long breathing tube found in other mosquitoes; adults have hairs, but no scales on the abdomen and both sexes have palpi as long as the probosis. Feeding females assume a distinctive pose with their abdomen pointed high in the air.

Western malaria mosquitoes occur west of the Rocky Mountains, between southern Canada and northern Mexico, and from sea level to about 6,000 ft. elevation. The larvae prefer clear, clean water, in sunlit or partially shaded streams or ponds. They occur in both Marin and Sonoma counties, but their highest density is found in the irrigated and seasonally flooded rice fields of the great central valley, historically the region of California's highest malaria infection rates.

Adults migrate in the spring and fall, but most stay within five miles of their larval sites. Like most Anopheles, they are active during the hours of darkness, and find shelter in hidden places during the day. Females feed mainly on medium to large mammals like rabbits, deer, cattle or horses, and they pursue and bite man aggressively.