BIONOMICS AND ECOLOGY OF NEABCTIO SPECIES 
83 
briefly discusses both predators and para¬ 
sites. Boyd (1930a) credits the nighthawks 
(Caprimulgidae) as being probably the 
most important bird enemies of anophelines. 
It is common knowledge that dragonflies 
catch mosquitoes while in flight, and that 
spiders take a heavy toll of resting mosqui¬ 
toes. In former years considerable pub¬ 
licity was given to the reputed value of bats 
as mosquito destroyers, but, although they 
undoubtedly catch many anophelines, ob¬ 
servations in places where bats are numer¬ 
ous have shown that in reality they have 
little effect in reducing the mosquito popu¬ 
lation (Howard 1916). 
Egg laying. Female anophelines deposit 
their eggs singly on the water surface dur¬ 
ing the night. Whether a selection of 
favorable breeding waters is made before 
oviposition is not known with certainty, 
although it can be inferred from the fact 
that even the more general breeders show 
a certain amount of segregation in differ¬ 
ent types of breeding places. It is, of 
course, plainly evident in the ease of the 
specialized forms such as A. barberi and A. 
atropos. Certain waters often contain only 
the first or second instars, indicating con¬ 
ditions unfavorable for their maturation. 
These have been termed incomplete breed¬ 
ing places in contrast to those where all 
immature stages occur regularly. In these 
cases, of course, failure to mature may be 
due to the activities of predators rather 
than to lack of adequate nutritional or 
other factors. 
From about 100 to 300 eggs are usually 
laid singly at one oviposition time and the're 
may be several oviposition periods for a 
single female. The eggs are white at first 
but soon turn to a dull black. The incu¬ 
bation period is usually about 2 days, 
although at high temperatures eggs may 
hatch in 24 hours (Mayne 1926a). The 
same author reports that oviposition did 
not occur below 55° F, and that eggs of 
A. quadrimaculatus would not hatch at 
temperatures of 58 to 59° F, but that 
hatching occurred at 66 to 70° F. 
Anopheline eggs will resist a certain 
amount of desiccation after the embryo is 
developed. Herms and Freeborn (1920) 
found that eggs of A. freeborni (“ quadri- 
maculatus”) would stand drying for 72 
hours, whereas drying for 24 hours was 
fatal to those of A. pvnctipennis. Mayne 
(1926a) found that eggs of A. quadrimacu¬ 
latus were viable after being left on drying 
mud for periods of from 42 hours to 16 
days. Eggs of A. crucians similarly ex¬ 
posed survived drying for periods of 10 to 
21 days. Larvae hatched and developed 
normally from these dried eggs. Control 
eggs in these tests hatched within 48 hours 
on the surface of water at the same tem¬ 
perature. Other observers apparently have 
not been able to duplicate these results. 
Larval Ecology 
Of the 13 species and subspecies of 
Anopheles that occur in the United States 
and Canada, 11 breed normally in fresh 
water and 2 in brackish or salt water. Both 
permanent and temporary, ponded and 
slowly moving waters are utilized. The 
most general characterization of anopheline 
breeding waters is that they are clean, foul 
or contaminated waters being seldom in¬ 
habited. Of the fresh-water species, A. 
quadrimaculatus, A. occidentalis, A. free¬ 
borni, A. crucians, A. pseudopunctipennis, 
and A. walkeri are what may be termed 
chiefly pool and pond breeders, A. free¬ 
borni and A. pseudopunctipennis being 
especially associated with pools in irrigated 
areas. A. punctipennis may occur in simi¬ 
lar locations to the foregoing but frequently 
also is found in moving water, particularly 
along the margins of streams. The larvae 
of A. barberi occur almost exclusively in 
water held in tree holes. They have been 
taken rarely in artificial wooden receptacles 
in shaded locations where accumulations of 
leaves and other decaying matter in the 
water make for conditions approximating 
those of tree holes. Of the two species 
inhabiting the salt marshes, A. atropos 
appears to be strictly a salt-water breeder, 
as it has not been found in fresh water. 
A. bradleyi (crucians bradleyi) breeds in 
waters of lower salt concentrations as a 
rule and also has been found in nearly fresh 
