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INSECTS AFFECTING MAN AND ANIMALS 
Destruction of ergs of horse botfly.--5. F. Knipling of ‘the Ames, 
Iowa, field laboratory, who has found that the eggs of Gastrophilus. — 
intestinalis De G. are very resistant to destruction by chemicals, has 
devised a method of decoying the larva from the egg by an artificial 
stimulus, after which it is more readily killed. he larva, ready: to. 
emerge, ordinarily remains within the egg upon “the hair ofthe horse 
until external conditions are favorable for emergence; and:it is dur— 
ing this stage that they are especially difficult to destroy. Mr. 
Knipling has used the simple expedient of dashing warm water on the. 
coat of the horse and has found this to be effective in inducing emer— 
gence of the larva from the egg. <A gradual rise in temperature does 
not bring about the response, however; the temperature rise up to about 
113° F. must be ‘rapid ‘to’ be effective. | % 
Use of aguatic saw aids in control of Mansonia larvae.—-T. E. Mc-— 
Neel, of the Orlando, Fla., laboratory, has used a Ziemsen aquatic sav 
to cut down Pontederia plants in.a pond having an infestation of larvae 
-of M. perturbans Wlk. The plants were cut about 10 inches below the 
water surface, and successful results were obtained both in the elimi- 
nation of the larvae and in the destruction of the plant srowth. Hight 
additional cuttings over smoll.areas have since been made with similar 
results. 
The existence of an unsuspected new species of screwworn.--H. C. 
Cushing, Menard, Tex., has returned from a 3-months! stay at the Liver- 
pool School of Tropical Diseases in England. With the cooperation of 
Dr. W. S. Patton of that adnstitution, Mr. Cushing, who has been making 
a microscopical study of the terminalia of specimens considered to be 
Cochliomyia macellaria Fab., has found among material collected in 
Texas the new species americana Cushing ond Patton. Owing to the fact 
that adults of the latter species were never found in traps, while 
macellaria is commonly cought in that way, the possibility is opened 
up that americana is not attracted by fetid odors--a typical character- 
istic of macellaria. Mr. Cushing is of the opinion that macellaria 
does not produce ‘myiasis and that. americana is the true screwworn of ths 
Western Hemisphere. THis. will. necessitate a reinvestigation of the 
biology, habits, and distribution of the two forms. Perhaps it may 
also require modification of control recommendations. 
Pest mosquito control work in cooperation with the C. W. A.--The 
work of getting under way this large-scale mosquito control project has 
required the’ combine’ efforts of practically the entire Washington of- 
fice force, which has been doubled by additional temporary emplayees 
provided by C. W. A. funds. In the 32 States and the District 6f Col-— 


