OTHER ANIMALS 657 



to say that only an infinitesimal proportion of them ever taste the 

 blood of a warm-blooded animal. 



Mosquitoes and Disease. The greatest impetus to the warfare 

 against mosquitoes was given by the recent positive demonstrations 

 that certain species are the camera of disease, that is, the agents 

 (germs) responsible for the disease are parasitic to certain mos- 

 quitoes during an intermediate stage in their developmental cycle. 

 In fact it has been proved in the case of yellow fever and malaria 

 that without certain species of mosquitoes as hosts, the life-cycle 

 of the organisms responsible for the disease is interrupted. This 

 has changed the mosquito problem from one of discomfort alone to 

 one of health also. The most complete work in preventive medi- 

 cine is the result of experiments along these lines. That yellow 

 fever and malaria are conveyed from diseased persons to healthy 

 people by bites of certain species of mosquitoes is an acknowledged 

 fact in recent medical literature. Aside from yellow fever and 

 malaria, mosquitoes are credited with the dissemination of ele- 

 phantiasis, filariasis, and possibly the dengue fever and leprosy. 

 The relation of certain insects to diseases, both plant and animal, 

 is a study which in the future will do much to prevent their present 

 serious work. 



The A bundant Mosquito, Culex Pipiens. The members of the 

 genus Culex are distributed generally over the world and seem to 

 be limited by neither altitude nor climate. The species so abundant, 

 Culex pipiens, is the common species of the genus and the mos- 

 quito whose life-history and habits are most generally known. This 

 mosquito is reported from all parts of the United States and is 

 recorded by Theobald as occurring generally in Europe. 



Breeding Places. The places chosen by the female of this 

 species for depositing her eggs are many and varied. There is, 

 however, a decided preference for certain places. Where there ia 

 a choice between water containing a supply of decomposing vege- 

 table or animal matter and uncontaminated water, the insect will 

 invariably choose the water containing the organic matter, serving 

 as it does as food for the young. The places mentioned by differ- 

 ent writers as the breeding places of this species of mosquito are 

 water-tanks, tubs and buckets under water-taps, wells, cisterns, bar- 

 rels, open sewers, cess-pools, swamps, small pools, wayside ditches, 

 empty oil tins, biscuit tins, sardine and tomato cans, gourds, flower 

 pots, vases, cuspidors, broken and unbroken bottles, crockery, pot- 

 tery and tins on rubbish heaps, hollow stumps, post-holes ana other 

 excavations left unfilled, fire-buckets, gutters and eaves which are 

 imperfect or which have become clogged, water-taps in sinks and 

 closets, wateringotrottghfl for stock, neglected lily ponds and foun- 

 tains, and catch basins from leaders. 



Life-History of Culex Pipicn*. The eggs of the night mos- 

 quito are easily observed in the places where they occur. They 

 appear a raft-like mass floating on the surface of the wator and 

 resemble a small piece of charcoal about one-fourth of an inch in 

 length. This manner of depositing the eggs is characteristic of the 



