316 MOSQUITOES OF NORTH AMERICA 



Ashbum and Craig have followed the development of Filaria philippinensis 

 in Culex quinquefasciatus but got only negative results with Aedes calopus. 

 There appears to be some doubt that this Filaria is a valid species but Looss con- 

 siders it distinct. 



Fiilleborn, in his experiments in Germany, used Anopheles maculipennis and 

 Aedes calopus. He found that Filaria hancrofti, F. perstans and F. demarquayi 

 underwent partial development in the Anopheles and then perished. One Aedes 

 calopus showed a developmental stage of Filaria demarquayi in the thoracic 

 muscles. With Filaria immitis of the dog Fiilleborn found that Anopheles 

 maculipennis became practically always infected. Aedes calopus became in- 

 fected in the proportion of one to five. Nevertheless he found this latter species 

 the more satisfactory for experimentation because, in the high temperature 

 necessary for the development of the filarise, the Anopheles suffered great 

 mortality. 



SUGGESTED RELATIONS OF MOSQUITOES WITH OTHER 



DISEASES. 



While it seems reasonable to suppose that mosquitoes, together with other 

 biting insects, may be responsible for the transfer of certain diseases which do 

 not necessarily require a secondary host for complete development, such rela- 

 tion has never been proved. They have been accused or suspected of being im- 

 portant agents in the transfer of leprosy, in the carriage of bubonic plague, of 

 tropical ulcer and other skin diseases, of Malta fever, of the horse sickness of 

 South Africa, and of otlier maladies, even of cancer. Some of these diseases 

 have never been satisfactorily investigated. With others it has been shown that 

 they are transmitted in other ways. Thus bubonic plague is now well known to 

 be transmitted by the bite of certain fleas and Malta fever is acquired through 

 the consumption of the milk of goats affected with this disease. 



EFFECT OF MOSQUITO BITES. 



The bite of nearly all mosquitoes causes some irritation but this varies in 

 degree with different species and with the individual bitten. It is by no means 

 always the largest mosquito which inflicts the most painful bite. Very serious 

 results have been attributed to mosquito bites. However, beyond a doubt, when 

 serious results follow these are due, not to the bite itself, but to the scratching 

 indulged in by the victim. In such cases it is the infection from the finger nails 

 which causes the trouble and this may indeed be serious. In sensitive persons 

 the inclination to scratch is well-nigh irresistible ; it will, however, be found that 

 if one exercises self-control in this respect the effect of even the severest bite will 

 pass very quickly. 



Eeaumur thought that a poisonous fluid was secreted by the mosquito and 

 that its purpose was to cause the blood to flow more readily when it bites. Later 

 observers either accepted this statement or denied the existence of such fluid, 

 stating that the swelling following the bite was caused by the irritation of the 

 puncture without the aid of a poison. Dimmock (1881) convinced himself that 



