ADAPTABILITY OF CONTROL MEASURES TO THE 
NEARCTIC FAUNA OF ANOPHELES 
MOSQUITOES 
By HENRY A. JOHNSON 
U. S. PUBLIC HEALTH SERVICE, WASHINGTON, D. C. 
Distinct faunal regions of anopheles 
mosquitoes have been observed and Boyd 
(1930a) has delineated these divisions geo¬ 
graphically. He classes in the Nearctic 
fauna those species of anophelines occur¬ 
ring in temperate and arctic North Amer¬ 
ica, including the United States, Canada, 
and Greenland. This paper will be limited 
to a discussion of malaria and of the con¬ 
trol of the anopheline vectors within these 
areas. 
Basic Problems 
“Although nine species of anophelines 
are represented in the Nearctic fauna only 
two are known to be important vectors of 
malaria, namely, A. quadrimaculatus and 
A. maculipennis. This is due to the par¬ 
ticular breeding habits of the insects and 
their associations with man. A. quadri¬ 
maculatus is the chief vector of malaria in 
the greater portion of the malarious sec¬ 
tions. It breeds almost wholly in still water 
that is relatively clean. It requires some 
sunshine, never being found in dense shade. 
It is not found in waters wholly unshaded. 
Although A. quadrimaculatus will feed on 
animals as do other anophelines it will 
also feed voraciously on human beings and 
frequents human habitations. An ideal 
breeding place for A. quadrimaculatus is 
in freshly impounded water which floods a 
basin containing some underbrush and 
which is sparsely covered with trees. Such 
water quickly gathers floatage, dying land 
vegetation, twigs, and leaves among which 
algae soon appear. Such floatage offers 
the requisite amount of shade and an abun¬ 
dant food supply. The supply of minnows 
and aquatic insects will seldom be sufficient 
to prevent mosquito production. 
“The normal detritus passing down a 
narrow stream will clog the interstices of a 
fallen tree or branch and create a dam. 
These natural impounded waters are excel¬ 
lent breeding places for A. quadrimacu¬ 
latus. Swamps covered by a growth of vir¬ 
gin timber on the other hand are not good 
breeding places. They have a small seed¬ 
ing of A. quadrimaculatus but not enough 
to perpetuate malaria. When the lumber¬ 
man enters, cutting out the large trees and 
leaving the small ones, the branches and 
tree tops, he changes a safe water surface 
into one almost ideal for A. quadrimacu¬ 
latus production” (Williams 1937a). 
Agriculture on the other hand usually 
has the reverse effect. Where land is at all 
valuable A. quadrimaculatus swamps and 
ponds are drained. 
In the river valleys of New Mexico, Cali¬ 
fornia and Oregon, A. maculipennis is the 
malaria vector of importance. This mos¬ 
quito breeds in waters which are constantly 
refreshed, such as overflows, seepage areas, 
continuous-flow-rice-irrigation and stream 
pools below the river level. It, therefore, 
is apparent that much of our malaria is 
man-made although such factors as climate, 
topography, and movements of population 
play an important part in its distribution 
and spread. 
Economic Resources 
Cities and large towns are normally pros¬ 
perous and they have been quick to take 
advantage of modern conveniences, such as 
water and sewerage systems, improved 
streets and drainage. Screens are almost 
universally used as protection from insects. 
The utilization of these conveniences has 
resulted in the elimination of anophelines 
