224. SANITARY ENTOMOLOGY 



segment and the extremity of the twelfth, there are delicate finger-like 

 processes, usually four in number, which serve as tracheal gills. The 

 pupa is free and either lives floating in water without any movement or 

 rests on the bottom of the pool. It has a tuft of delicate white threads 

 on the dorsum of the thorax, which serve as breathing tubes ; or it may 

 have a pair of respiratory trumpets. 



Tersesthes torrens Townsend, a mountain form in North America, is 

 a voracious bloodsucker, attacking man and animals, usually on the head, 

 ears, and eyes. Its life history is unknown. 



Mycterotypus bezzii and M. irritans of Southern Europe are vora- 

 cious bloodsuckers, biting human beings, as well as animals, and causing 

 inflammatory swellings. 



Ceratopogon is a large genus containing a number of bloodsucking 

 gnats called "punkies," found in various parts of the world. Some of the 

 Asiatic species attack bloodsucking mosquitoes and draw blood from 

 them. It is therefore possible that these insects may play a role in disease 

 transmission. They are very small, measuring less than 3 mm. in length. 

 Only the females are bloodsuckers. They bury themselves often among 

 the hairs of the host and are not recognized until they become replete 

 with blood. They often cause great distress on account of their num- 

 bers and the irritation produced by their bites. The different species 

 choose different parts of the host for attack, as for example, some select 

 the face, especially the margins of the ears and eyes, while others may 

 attack the arms or legs. 



Forcipomyia utae Knab is thought by Townsend to cause the South 

 American disease, uta. Forcipomyia is considered to be a subgenus of 

 Ceratopogon. Larvae have been found in crab holes and below the algal 

 crust on the sand along the seashore in South America. 



Culicoides is another large genus of midges vary similar to Cera- 

 topogon, and contains many bloodsuckers. Only the females bite. The 

 larvae are found in water under various conditions. When searching for 

 larvje where the adults are abundant, they may be found by gathering 

 in a white tray some of the green vegetable matter found at the edges of 

 streams. The flies can be bred by placing the pupae on moist filter paper 

 in tubes closed with moist cotton. 



The genera Johannseniella and Haematomyidium also contain blood- 

 sucking midges. 



FAMILY SIMULIIDAE 



Buffalo Gnats 



The buffalo gnats of the genus Simulium are sometimes also called 

 sand fiies and turkey fiies. This is a large genus of voracious flies which 

 often are so numerous as to cause great distress and even death to men 



