THE FLIES THAT CAUSE MYIASIS IN MAN 127 



6. Thorax gray, with more <»r less distinct traces of 2 to 4 vittae ; anterior 



tibia with a small but distinct anterodorsal bristle somewhat basad to 

 the preapical one 7 



Thorax blackish gray, without traces of vittae: anterior tibia without a 

 smaller anterodorsal bristle basad to the preapical one. 



manicata (Meigen), female 



7. Ocular orbits and mesonotum densely grayish pollinose; middle fenrar 



with an outstanding, though rather slender, bristle at the base below. 



scalarix (Pabricius), female 

 Ocular orbits and mesonotum sparsely grayish pollinose; middle femur 

 with only a short fine hair below at the basn. 



incisurata (Zetterstedt), female 



THIRD-STAGE LARVA?: 



1. Lateral processes of the abdominal region spinulose only on the basal 



region, not pinnate; dorsal processes similar in nature to and almost as 



long as the lateral ones canicularis (Linnaeus) 



Lateral processes pinnate at least almost to the apex; dorsal processes 

 less than half the length of the lateral ones 2 



2. Dorsal processes well developed, though small, and spinulose. 



scala ris (Fabricius i 

 Dorsal processes reduced to sclerotized buttons, scarcely or not at all 

 evident 3 



3. Lateral processes large and strongly developed, the branches of ad- 



jacent ones touching, or almost so incisurata (Zeuerstedt) 



Lateral processes relatively small, the branches of adjacent ones not 

 nearly touching manicata (Meigen) 



FANMA SCALARIS (Fabricius) 



The Latrine Fly 



Synonyms. — Homalomyia scalaris (Fabricius); Fannin saltatrix Robi- 

 neau-I>esv<>idy. 



Recognition Characters. — Adult : This is a slender fly. about 6-7 mm. in 

 length ; the body is black, the legs likewise black except the knees and the bases 

 of th^ front tibiae. The parafrontals and parafacials are silvery: the thorax 

 and abdomen gray-dusted, the former with two brownish vittae, the latter with 

 a black median band. Larva (fig. 70) : The antennalike processes of the pro- 

 thoracic segment are very short: the lateral pr< -cesses of the other segments 

 are Long and pinnate to their apices, their length increasing progressively back- 

 ward. Dorsally. the segments of the thorax, except the first, each bear a pair 

 of short spinous tubercles : the segments of the abdomen, except the last, have 

 similar but more strongly developed processes. The anterior spiracles end in 

 six to eight, usually seven digitate processes. The length of the mature larva is 

 about 6 mm. 



Geographical Distribution. — Nearctic Region : Labrador. Nova Scotia, Quebec, 

 Ontario, Alberta. British Columbia. Maine. New Hampshire. Massachusetts. 

 Rhode Island. Connecticut, New York. New Jersey, Pennsylvania. Maryland, 

 District of Columbia, Virginia. North Carolina. Tennessee. Indiana. Iowa, South 

 Dakota, Kansas. Texas. Montana, Idaho. Colorado. New Mexico. Arizona, Wash- 

 ington, Oregon, California. Neotropical Region : Chile, Argentina. Palaearctic 

 Region: Ireland. Scotland. England. Spain, France. Netherlands. Belgium. Italy. 

 Corsica, Norway. Sweden. Finland. Lapland (Swedish). Denmark. Germany. 

 Poland. Austria. Hungary. Yugoslavia. Rumania. European Turkey. European 

 Russia (widespread), Caucasus. Azores, Canary Islands. Morocco, Palestine. Rus- 

 sian Turkestan, Manchuria. Chosen, Japan. Ethiopian Region: South Africa. 



Life History and Pathogenesis. — The larvae have been recorded 

 as breeding in decaying fungi, cadavers, birds' nests, nests and burrows 

 of Hymenoptera. and excrement. They are common in privies, and 

 Lesne ( 82) records them as common, though not nearly so much as 

 F. incisurata^ in cesspools in the vicinity of Paris. The eggs hatch 

 in a short time, often 2 days or less : the life cycle in temperate climates 



