26 



PARASITES OF THE DOMESTIC ANIMALS 



pupal case at the thorax, there is an apparent adaptability in this re- 

 versal of position. 



The common house or ''rain barrel" mosquito of the Northern 

 United States, Culex pimgens (Fig. 12), breeds throughout the summer, 

 broods developing wherever there may be standmg water, as in pools, 

 troughs, cans, discarded bottles, gutters, etc. The adults of this species 

 may pass the winter in the shelter of darkened retreats, such as the 

 cellars of houses, behind furniture, outbuildings, and wood piles, 

 emerging from their hibernation in the spring to deposit their eggs. 

 Many first spring broods in temperate climates hatch from eggs that 

 have been carried over the winter months, the eggs seeming to stand 

 desiccation in dry locations to promptly hatch in pools left by the spring 



Fig. 11. — Pupa of Culex pungens at left; pupa of Anopheles quad- 

 rimaculatus at right — greatly enlarged (after Howard, Bui. No. 25, 

 Bureau of Entomology, Dept. of Agr.). 



rains, or even in water from melting snow during the warmer days of 

 late winter. 



In refutation of the assertion often made that mosquitoes cannot 

 ovulate without a meal of warm blood, it has been demonstrated in 

 experiments upon some of our common blood-sucking species that fe- 

 males as well as males can not only be kept alive for a long period when 

 given access only to plants, but will, under such conditions, repeatedl}^ 

 breed. 



Pathologic Importance. — While their preference for blood has made 

 them of primary general interest as pests in the habitations of man, 

 mosquitoes are of the greatest importance medically, not only as possible 

 direct transmitters of disease, but as specific bearers of infection, bring- 

 ing about such diseases as malaria, yellow fever, and possibly filariasis. 

 There have been many convincing demonstrations that malaria is 

 transmitted exclusively by the bite of mosquitoes, only, however, by 

 species belonging with the anopheles group, of which Anopheles quadri- 



