CONTROL MEASURES FOR NEARCTIC MOSQUITOES 
357 
Naturalistic Methods Other Than Top 
Minnows 
These methods consist of so altering the 
environmental or the chemical or physical 
characteristics of breeding areas that they 
are no longer attractive to anophelines. 
Methods which possibly may be effective 
against the Nearctic fauna may he repre¬ 
sented by the following: increasing salinity 
of the water; polluting the water by sew¬ 
age, laundry or other wastes; filling by 
deposition of silt; introducing predacious 
insects; shading, or other method of con¬ 
trolling food supply, but their possibilities 
with our fauna have not been explored. 
Under certain conditions the above meth¬ 
ods might be utilized to change the mos¬ 
quito fauna, but the possible substitution 
of very bothersome noxious species for 
Anopheles larvae should be considered. 
These methods can now be made effective 
only under certain conditions, but when 
factors limiting Anopheles production are 
more thoroughly understood, naturalistic 
methods of control may become of decided 
importance. Certainly the possibilities of 
naturalistic control possess potentialities 
which merit study. 
Miscellaneous 
"While the foregoing methods are in gen¬ 
eral use for anopheline control, certain 
other methods or combination of methods 
may be useful under special circumstances. 
Instead of draining a swamp or seepage 
area, it is sometimes desirable to deliber¬ 
ately increase the retention of water as a 
mosquito control measure, in order to 
facilitate the application of Anopheles 
control measures at the prepared edges. 
The value of shading by tall bushes or 
trees as an anopheline control measure has 
been the subject of much discussion. Shad¬ 
ing is a recognized measure for the control 
of some Anopheles of the old world and has 
been suggested for the control of A. quad- 
rimaculatus. Long standing densely shaded 
swamps, never lumbered, do not support 
A. quadrimaeulatus. Reshading of the 
lumbered swamps with quick growing low 
bushes has not been effective. Other types 
of shade should be tried. 
A. maculipennis, the malaria vector of 
the west and southwest, is often produced 
in seepage water resulting from poorly ap¬ 
plied or excessive irrigation water. It is 
much more practical to correct the condi¬ 
tions either at the source or by drainage, 
than to render them inoperative by creat¬ 
ing shade. "Where large seepage areas from 
irrigation cannot be prevented, the produc¬ 
tion of A. maculipennis can be controlled 
by the liberal use of larvicides aided pos¬ 
sibly by minnows. 
Nearctic anopheline fauna are attracted 
to animals as well as to man, and this fact 
has led to the trial of animal barriers 
(stabling of animals) between known 
anopheles producing areas and a popula¬ 
tion it was desired to protect. This might 
be termed a biological method of control 
and there is evidence to show that under 
ideal conditions some protection is afforded. 
However, opportunities for using this 
method effectively are so few in the area of 
the Nearctic fauna that it is at present of 
little practical importance. 
An effective method of preventing the 
spread of malaria by controlling adult 
anophelines consists in- systematically kill¬ 
ing them in the home each morning. 
Spraying with pyrethrum extract serves a 
similar purpose, and has been used in con¬ 
nection with the control of Anopheles gam- 
hiae in Brazil. These methods are designed 
to prevent the flight of infected Anopheles 
and were used very successfully by J. A. 
Le Prince (1926) at Panama when other 
means of malaria control (particularly 
screening) were not available. Its chief 
use would naturally be in temporary labor 
or military camps in malarious areas where 
anopheles were abundant and other means 
of malaria prevention impracticable. Al¬ 
though the method has apparently not been 
tried in North America, there are circum¬ 
stances when it would seem to offer possi¬ 
bilities. 
In discussing the applicability of the 
various measures of mosquito control for 
