BIONOMICS AND ECOLOGY OF NEARCTIC 
ANOPHELES 
By G. H. BRADLEY and W. V. KING 
BUREAU OP ENTOMOLOGY AND PLANT QUARANTINE, UNITED STATES DEPARTMENT OP AGRICULTURE, 
WASHINGTON, D. C. 
In common with, all mosquitoes, anophe- 
lines have four stages in their life cycle— 
the egg, the larva, the pupa, and the adult. 
The life history is briefly as follows: The 
eggs, which are laid singly on the water sur¬ 
face, hatch in from 2 to 3 days, under favor¬ 
able conditions, into larvae, or wigglers. 
These grow slowly or rapidly, depending on 
temperature and other factors, spending 
from a week or so to several months in this 
stage. The larva molts four times, the final 
molt being into the pupal, or tumbler, stage. 
During the pupal stage changes take place 
within the body which transform it into the 
adult mosquito. This stage is usually com¬ 
pleted in from 2 to 3 days, and after the 
adult emerges from the pupal case it rests 
for a short time on the surface of the water 
before taking flight. 
Adult Behavior 
Mating. Anopheline adults are usually 
produced in approximately equal numbers 
of males and females, although a pre¬ 
ponderance of females sometimes occurs 
(Bradley 1926; Boyd 1930a). For the 
species that have been observed, mating 
occurs about sundown during swarming of 
the males. In the case of A. punctipennis 
the male swarm consists of about 100 indi¬ 
viduals flying up and down in corkscrew 
fashion from 7 to 12 feet above the ground 
(Howard, Dyar, and Knab, 1912-17a, v. 1, 
p. 127). Freeborn (1923) observed swarms 
of A. maculipennis ( occidentalis) and of 
A. quadrimaculatus in close proximity to 
one another near a pond in Massachusetts, 
one of which was above a small pine tree, 
the other in the open. 
Longevity and number of generations. 
The duration of adult life varies greatly, 
being shortest during the hot, dry weather 
of the summer and longest during the fall, 
particularly with those females that go into 
hibernation. Humidity, as well as tempera¬ 
ture, is an important factor in longevity. 
The life of the male is probably shorter in 
all cases than that of the female, and they 
are not known to hibernate. The appear¬ 
ance of males in the spring is usually taken 
as indicating the emergence of the first 
brood of the season. 
The number of generations of Anopheles 
in any region probably depends largely on 
the climate, inasmuch as it is known that 
high temperatures accelerate and low tem¬ 
peratures retard development. The num¬ 
ber of generations has been studied for A. 
quadrimaculatus . by Boyd (1927), who 
believes that this species may have from 8 
to 10 generations annually in southwestern 
Georgia, while in northeastern North Caro¬ 
lina the number is 7 or probably 8. Free¬ 
born (1932) states that in California there 
are 6 generations of A. maculipennis 1 
annually. 
Biting activity. Female anophelines seek 
blood meals within a day or two after 
emergence when the mouthparts are suffi¬ 
ciently hardened and conditions for flight 
are favorable. For most of the species 
feeding activity is probably greater soon 
after dusk, but it may continue throughout 
the night. Most of the species will bite 
during the daytime on dark days or in shel¬ 
ters, particularly if disturbed. A. atropos 
provides a striking exception to this gen¬ 
eralization, however, for in addition to 
being active during the night, it has been 
observed at times to attack in swarms in 
bright sunlight. A. crucians (the common 
i Probably A. freeborni in this and other refer¬ 
ences to maculipennis in California, except where 
the coastal form with pale wing tips is referred to. 
