49 



swarming with the larvte of Culex ptnu/ens^ C sthnulmis, and O. per- 

 turhan^; also with the larva of an Eph ydrid — Br<tchydeatera argerddta 

 Walk. — and with the larva of an P^phemerid of the genus C^enis, and 

 other aquatic species. A number of specimens of Hydrophilid larvae 

 were found by the writer in this pool. They fed upon the other 

 aquatic insects with avidity, and three of them were placed in a larg-e 

 batteiy jar ^\\\\\ aboiit a half gallon of this water, teeming with insect 

 life and containing apparently some hundreds of the mosquito larva? 

 and many of the others just mentioned. These three Hydrophilid 

 larv», in the course of a week, practically devoured all of the other 

 animal life in the jar. Only two male mosquitoes and one female suc- 

 ceeded in reaching the adult stage. 



No one can realize the intensity of the struggle for existence which 

 is going on in a stagnant pool until he forces himself to the seemingly 

 rather unpleasant occupation of lying down by its side and watching 

 with a large hand lens the various forms of life with which the water 

 is swarming. Aside from the larvte of the dragon tiies and the preda- 

 tory larva? of the three great families of aquatic beetles, namely, the 

 Dytiscidse, the Hydrophilida% and the CTyrinida\ there are aquatic 

 neuropteroid insects which are predatory and which feed upon 

 mosquito larvas as well as others, like those of the genus Hydro- 

 psyche; and there are aquatic Heteroptera which are also predatory 



Aside from insects, there are many other natural enemies of mosqui- 

 toes. Many tish eat their larv» and pupa?, and such night-%ing birds 

 as nighthawks and whip-poor-wills, and bats as w^ell, destroy the adults. 

 Harvey (American Naturalist, 1880, p. 896), quoted by Mrs. Aaron, 

 found 600 mosquitoes \i\ the crop of a nighthawk. 



REMEDIES AGAINST MOSQUITOES. 



Remedies hi. houses and the 'jyreveidion. of hides. — Of the remedies in 

 use in houses the burning of pyretliium powder and the catching of 

 mosquitoes on the w^alls in kerosene cups are pro])a])ly the best, next 

 to a thorough screening and mosquito bars about the })ed. In burning 

 pyrethrum powder it is well to moisten the powder sufficiently with 

 water so that it can be molded roughly into little cones about the size 

 of a chocolate drop. These cones are placed on a pan and dried in 

 the oven. If ignited at the apex the cones smolder slowly, giving off 

 an odor not unlike that of the prepared punk which boys in this 

 country use to light firecrackers. Two or thrcM? of these cones burned 

 in a room in the evening will give relief by stupefying the mosquitoes. 

 This smoke appears to be perfectly innocuous to human beings. The 

 writer has breathed it evening after evening without the slightest per- 

 ceptible ill effect. The method of catching moscjuitoes on the walls 

 with kerosene in cups is now in frequent use in different parts of the 



