98 MISC. PUBLICATION 631, U. S. DEPT. OF AGRICULTURE 



work toward the mucous lining- of the mouth, the subsequent migration 

 to the stomach taking about a month. 



Known cases of parasitism in man are not common, but several have 

 been recorded within the range of this species in North America and 

 Europe. According to Austmann, cases in man tend to occur most 

 frequently on the face and buttocks. 



GASTEROPHILUS NASALIS (Linnaeus; 



The Throat Bot ; the Chin Fly 



Synonyms. — Oasterophilus veterinus (Clark) ; Rhinogastrophilus nasalis 

 (Linnaeus) of Townsend's Manual. 



Recognition Characters. — Adult : The body is mainly blackish or brownish- 

 black in background, the head, however, being reddish yellow ; the pile is chiefly 

 pale, that of the thorax being mainly reddish yellow, and that of the abdomen 

 whitish or pale yellow, with a broad band of black pile crossing the intermediate 

 segments. In the wing the two basal cells are of approximately equal length, the 

 vein m 3 being nearly even with the cross vein r-m. Length 10-15 mm. Larva : 

 Readily distinguishable from G. haemorrhoidalis and G. infest inalis by the char- 

 acters given in the key and by figures 43, A and 43. B. The first-stage larva is 

 much more slender, more nearly cylindrical, and more supple than the two 

 species just mentioned. 



Geographical Distribution. — Nearctic Region : Nova Scotia, Northwestern 

 Territory, Quebec, Manitoba, Saskatchewan, Alberta, British Columbia, New 

 York, New Jersey, Maryland, Ohio, Michigan, Illinois, Kentucky, Minnesota, 

 Iowa, Missouri, North Dakota, South Dakota, Nebraska, Kansas, Oklahoma, 

 Texas, Montana, Wyoming, Colorado, New Mexico, Arizona, Washington, Oregon, 

 California. Neotropical Region : Jamaica, Puerto Rico, Antigua, Venezuela, 

 Chile, Argentina, Panama. Palaearctic Region : France, Netherlands, Italy, 

 Denmark, Germany, Austria, Rumania, Bulgaria. European Russia (widespread, 

 southern part), Morocco, Egypt, Cyprus, Turkey, Iraq, Siberia (Tomsk), Turk- 

 estan, Semiretchje, Mongolia, China. Oriental Region : India. Ethiopian Re- 

 gion: French Guinea, Kenya. South Africa (Transvaal, Natal, Cape of Good 

 Hope). Australian Region : Australia (Queensland), Tasmania, New Zealand, 

 Fiji, Hawaiian Islands. 



Life History and Pathogenesis. — On the normal host, the horse, the 

 eggs are deposited on hairs beneath the jaws. Each female produces 

 on an average about 450 to 500 eggs, the number in various counts 

 ranging from 304 to 518. The larvae hatch in about 6 days and crawl 

 into the horse's mouth, where they enter the mucosa of the cheeks or 

 form pockets between the molar teeth, to complete the first instar. 



This species has been accused of producing myiasis in man, but rec- 

 ords of such may be the result of misidentification. 



The Family CUTEREBRIDAE 



This family is here considered in the sense used in Townsend's 

 "Manual of Myiology" ; it is approximately equivalent to the Cutere- 

 bridae of Curran's "North American Diptera," except that that work 

 omits the genus Cephe?ie?nyia and consequently the characterization 

 of the family is not complete. 



These flies are rather large ; the more typical ones are bare or clothed 

 with short hair, which may, however, form dense patches or even 

 cover the thorax; one genus, Cephenemyia, resembles the bumblebee 

 in appearance. The face is sunken, sometimes with a carina; the 

 clypeus is narrow; the mouth parts are small or rudimentary, the 

 flies being unable to take food in the adult stage. The chaetotaxy is 

 usually undeveloped. The squamae are large; there is no 

 postscutellum. 



