tinued observation, experimentation, end, large-scale. application, of the 
knowledge thus gained to specially chosen areas. Dey wwe eee 
' 20) The! work of J. Lyell Clarke, in Illinois, while it hes not entire~ 
Ly: passed the experimental stage seems to. be an outstanding example of the 
application of. conservation principles to mosquito control through the 
‘partial substitution of biological methods for mechanical drainage. . The 
favorable experimental results of mosquito control by biological means 
have been for a great many years available in the literature on the subject. 
“While there’ is ‘need for further experimentation on. biological methods of 
control, it is certain that the known possibilities have been by no means 
exhausted. For -éxemple, much success in mosquito control abroad has at= 
tended the introduction of our native top minnows. It would seem logical, 
therefore, to experiment in this country with exotic species of the same 
nature to determine the feasibility of supplementing our native species 
with others that may be more effective.. Reports indicate that. many species 
of native and exotic fishes, perticularly top minnows, killifishes, and 
sunfishes, have been locally effective in controlling the mosquito pest. 
The Limitation and extent of effectiveness of these end other forms.should 
pe detérmined. Other biological agents of control that already have some 
promise include a horde of predecious insects, spiders, hydrachnids and 
other water mites, paresitic nematodes, trematodes, protozoa, bacteria, 
fungi, end many species of plants, especially Utricularia, Lemna, 
Spirodéla, Wolffie, and possibly certain of the odoriferous Characeote 
-It should be remembered that a slight alteretion of en aquatic or marsh 
environment may shift the ecological balance to favor any or all. of these 
orgenismS. Wes aad ere aay? : 
In importent wildlife ereas, especially where permanent ponds are 
involved, mosquito control should be attempted by biological methods - 
rather than by mechanical dreinege. . The biological methods ordinarily im- 
prove rather than destroy wildlife habitat and aid in preventing an over—con= 
‘centration of animal life in those areas where it can be more easily ex- 
tirpated. Ponds that periodically go dry cen be connected by: shallow 
ditches to permanent bodies of water that serve as reservoirs for larvar~ 
devouring organisms, so that when wet seasons occur netureal meens of 
control will be always available. pe tod an =e ey eae 
‘Such methods of mosquito control are acceptable to conservationists. 
The diking and impoundment of water for the accomplishment of mosquito 
ae control by biological means also find favor with conservationists, es- 
ft oj) pecially when provision is assured for structural maintenance. In de- 
3 +4 vising schemes of control, therefore ,' there should be close cooperation 
between conservation and mosquito-control authorities from the: inception 
of a project to its completion in an area involving wildlife or its habitat. 
Each ares should be considered as a separate unit and the control. methods 
selected should be applied to suit local conditions, so as to effect satis- 
factory mosquito elimination and the conservation of important wildlife 
habitat. / de ae a NG 
Severel examples of successful coordination of wildlife-conservation 
and mosquito-control interests in the prosecution of projects can be cited, 
Mention has already been made of the outstanding cooperation enjoyed. in 
the control projects under the Supervision of J. Lyell Clerke in Illinois. 
In Maryland, wildlife interests have been protected by &. L. Crosthwait, 
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