1906 ENTOMOLOGICAL SOCIETY. 35 



they are also the only agents; the life cycle of the malarial Plasmodia 

 being now fully understood. In a patient suffering from malaria the singk 

 celled protozoons are present in the red blood corpuscles, each of which fur- 

 nishes nutriment for one Plasmodium which matures and reaches the repro- 

 ductive or sporulating stage in 24, 48 or 72 hours, accordiui^j to its kind. 

 When ripe, the cell bursts and the pores are d^ischarged into the blood serum. 

 As all the organisms mature at practically one time, this general sporulatioa 

 upsets body conditions and a "chill" results. The spores work their way 

 into new corpuscles and the cycle is repeated. After a time bodies are pro- 

 duced that make no attempt to enter new corpuscles ; but remain in the blood 

 serum. These are the "gametes" or sexed forms of the animal and they 

 undergo no further development in man. If an Anopheles viacuUpennis now 

 bites the patient, it will take in with the blood some of these gametes which, 

 as soon as they get into the mosquito stomach differentiate. The smaller 

 forms or micro-gametes prodxice "flagellse," which break off and conjugate 

 with the larger or macro-gametes, the product of the union forming a "ver- 

 micule," which works into the tissue of the mosquito stomach. This developes 

 into a "zygote" and, in about a week that becomes mature, bursts and liber- 

 ates into the body cavity, thousands of "blasts" which, sooner or lat-er find 

 their way into the salivary glands. Now, when such a diseased mosquito 

 bites a healthy subject, some of the "blasts" are introduced into the wound 

 with the saliva and, if the subject is susceptible, a case of malaria is estab- 

 lished; the "blasts" working their way into the red blood corpuscles and 

 starting the vegetative cycle. 



The species of Anopheles select quiet pools of water bodies as breeding 

 places and, floating on the surface can maintain themselves in shallows out 

 of reach of most fish. The adults do not ^y lav and local work is likely to be 

 be effective. 



Some mosquitoes migrate or fly for long distances from their breeding 

 places and among those are the species that breed in the salt marshes which 

 occur so generally along the New Jersey coast. These breed as readily 15 

 salt as they do in fresh water and their influence extends inland 40 miles at 

 least. In New Jersey this species is dealt with by ditching work, which gets 

 rid of surface water before the larvae have a chance to develop. The eggs 

 of these migratory species are laid in the marsh mud and in that stage thej 

 pass the winter. The high tides of spring furnish water for the.ir development 

 and the broods begin early in May. The specimens that fly far inland are 

 all females, and all of the migrants are infertile. 



Filling as well as ditching is practised in some places, and much of the 

 Brooklyn rubbish is gathered in huge tanks, transported on trolley flat care 

 and dumped on the marshes of Gravesend Bay near Coney Island, N.T., to 

 the material advance of comfort in that resort. 



The common house mosquito, Cwlex pipiens, breeds anywhere and in 

 liquids of all kinds from decently clean water to sewage and even liquid 

 manure. It forms an egg boat and is the only species that agrees in all re- 

 spects with the early published accounts of mosquitoes. It is not a carrier 

 of any disease known in our climate and it is more as a first class nuisance 

 than as a danger to health that it challenges attention. Local work is very 

 effective against this species, and, indeed, only local work is likely to be of 

 any benefit, since the species is not a traveller. 



There is no sort of place where water occurs where mosquitoes will not 

 breed, and even tree holes have their own fauna. In New Jersey one species 

 of Anopheles and two species of Culex occur nowhere else. 



