THE FLIES THAT CAUSE MYIASIS IX MAX 77 



The Genus POLLENIA Robineau-Desvoidy 



The species of this genus are dull blackish flies, of medium size. 

 and more or less covered with grayish pollen : the thorax, in addi- 

 tion to the pollen, bears a number of yellowish or grayish, soft, crinkly 

 hairs of characteristic appearance. The eyes are narrowly separated 

 in the male, widely so in the female: the antennae are separated by 

 a narrow carina : the arista is plumose almost to the apex. The 

 propleura and prosternum are bare. The abdomen is oval and flat- 

 tened. 



Keys to the species of western Europe are given by Seguy (135), 

 and to those of the Oriental Region by Senior White. Aubertin. and 

 Smart (139). These authors employ a broader concept than that 

 indicated by the generic diagnosis given here. Only one species, P. 

 rudis : is known to occur in North America. 



POLLENIA RUDIS (Fabricius) 



The Cluster Fly 



Recoottion Chabactebs. — Adult : This Is a blackish fly with a tesselated 

 abdomen. The parafacials bear short black hairs; the palpi are black; the 

 squamae are bare : the metathoracic spiracle is reddish haired ; and the first 

 posterior cell is open. Length. 7-9 mm., sometimes larger. Larva : The mature 

 larva is rather smooth, the spines being small and colorless; the last segment 

 bears eight protuberances, only the anal pair being strong ; each anterior spiracle 

 has four apertures at the ends of fingerlike processes; the posterior spiracle has 

 three straight slits, a definite button, and a weakly sclerotized peritreme. 



Geographical Distribution. — Xearctic Region: Nova Scotia. Prince Edward 

 Island. New Brunswick. Quebec. Ontario. Manitoba. Saskatchewan. Alberta, 

 British Columbia. Maine. New Hampshire. Vermont. Massachusetts. Rhode Is- 

 land, Connecticut. New York. New Jersey. Pennsylvania. Maryland. District of 

 Columbia, Virginia. West Virginia. North Carolina. Georgia. Florida. Tennessee. 

 Ohio, Michigan, Indiana. Illinois, Minnesota. Wisconsin, Iowa. Idaho. Colorado. 

 Utah. Nevada. Washington, Oregon, California. Palaearctic Region: Ireland. 

 Scotland. England. Portugal. Spain. France. Netherlands. Switzerland. Italy, 

 Corsica, Sicily. Norway. Finland. Lapland. Denmark. Germany. Czechoslovakia. 

 Austria. Hungary, Rumania. Bulgaria. European Russia (north to Arkhangelsk). 

 Azerbaijan. Azores. Canary Islands. Madeira. Morocco. Tangier. Syria. Siberia 

 (Kongaus), Sinkiang. China. Oriental Region : India. 



Biology and Pathogenesis. — The larvae develop as internal para- 

 sites within the bodies of earthworms. The adults enter houses in 

 great numbers during the winter, especially in the more northern 

 parts of their range, and sometimes cause considerable annoyance. 



The larvae have been reported as involved in enteric myiasis in man ; 

 however, such records need verification before they can be accepted. 



Literature. — An extended study of the biology and immature stages 

 has been made by Keilin ( 65 ) . 



The Genus AUCHMEROMYIA Brauer and Bergenstamm 



This is a genus of medium-sized yellow flies. The eyes are bare and 

 broadly separated in both sexes, the front being about one-fourth the 

 width of the head, a little narrower in the male than in the female. 

 The arista is long-plumose almost to the tip. the hairs being a little 

 shorter below than above. The female has one proclinate fronto- 

 orbital; these are lacking in the male. There are two sternopleurals. 



