6 American Midland Naturalist Monograph No. 3 



causative agent of Bancroft's filariasis, is the species most frequently en- 

 countered in this disease, but in the Asiatic-Pacific zone Wuchereria malayi 

 also occurs. The disease is endemic throughout the moist, warm regions of 

 the world from about 36° N. to 25° S. latitude. In the Americas it is sporadic 

 from about Central Mexico to Argentina, being confined on the mainland 

 to coastal areas and river valleys. The West Indies and adjacent islands are 

 endemic centers. More than 50 species of mosquitoes are reported to be 

 natural or experimental vectors of filariasis. The following genera are repre- 

 sented: Ciilex, Aedes, Mansonia, and Anopheles. 



Heartworm of Dogs. — Mosquitoes belonging to the genera Culex, Ano- 

 pheles, and Aedes, are known to transmit Dirofilaria immitis, a parasitic 

 nematode found in dogs, cats and various wild carnivores. The worms invade 

 the heart (usually the right ventricle) and the pulmonary artery of the host 

 where they often form tangled knots and may cause the death of the host. 



Mosquito-Borne Encephalitides. — These consist of several immunologically 

 distinct epidemic virus diseases which have an affinity for the central nervous 

 system and may be disseminated by the bites of arthropods, including various 

 mosquitoes. The diseases are closely related both epidemilogically and clini- 

 cally. The principal types are classified as follows: Equine encephalomyelitis 

 (Eastern strain, Western strain and Venezuelan strain), St. Louis encepha- 

 litis, and Japanese B encephalitis. 



Culex tar sails, C. pipiens, Culiseta inornata and Anopheles ynaculipennis 

 freeborni have been found naturally infected with the virus of western equine 

 encephalomyelitis and the disease has been transmitted in the laboratory by 

 mosquitoes belonging to the genera Aedes, Culex and Culiseta. Culex tarsalis 

 and C. pipiens have been found naturally infected with the virus of St. Louis 

 encephalitis and several species belonging to the genera Aedes, Culex, and 

 Culiseta will transmit the virus experimentally. Culex tritaentorhynchus is 

 believed to be the principal vector of Japanese B encephalitis. 



Mosquito Vectors of Dermatobia. — Eggs of the tropical warble fly (Der- 

 matobia hominis) are carried by mosquitoes belonging to the genera Aedes, 

 Culex, Trichoprosopon, Haemagogus, Wyeomyia, Mansonia, Anopheles, and 

 Psorophora. Psorophora lutzii and P. ferox are considered to be important 

 carrier hosts in Central America and northern South America. 



Other diseases which may be transmitted by mosquitoes are leishmaniasis, 

 tularemia, fowl-pox, and Rift Valley fever. 



Technique 



Collecting Adults 



Due to the varied habits of different species of mosquitoes, many types 

 of adult collections made in different situations may be required to obtain 

 a satisfactory picture of the mosquito population in an area. Many kinds of 

 mosquitoes are attracted to relativelv dark shelters with little air movement 

 and a high atmospheric humiditv for their davtime resting. Some species 

 remain outdoors, apparently avoiding dwellings, and are commonly referred 



