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MR. G. S. COTTERELL ON THE LIFE-HISTORY 



stercoraria L., belonging to the family Cordyluridse of the 

 Acalyptrate Diptera. 



A description of the species is given in a monograph by 

 Becker, which is at present the standard work on the classilication 

 of the family Cordyliirida^. 



Both sexes vary from very large and robust flies to small 

 varieties. The largest measures 15 mm. in length and the 

 smallest 8 mm. The span of the wings is over double the length. 



The head is globular ; the eyes oval, brown, and separated in 

 both sexes by an area equal to half the width of the head. The 

 frontal stripe is rich yellowish brown in the male, dull yellow in 

 the feniale. The frontal margins of the orbits, cheeks, and face 

 are yellow. The facial bristles are strong ; antenna black, and 

 the arista bare except for the upper third, which is feathered. 



The thorax of the male is marked with longitudinal stripes on 

 the dorsal surface. There is a bunch of light yellow hairs under 

 each wing. The thcrax of the female is coloured darker, the 

 stripes more marked, and the hairs below the wings are absent. 

 Both sexes have more than two rows of acrostical bristles, and 

 well-marked scutellar bristles. 



The wings are slightly yellow ; anterior cross-veins very 

 distinct, with a smoky coloration round them. 



The femora are covered with long yellow hair in the male, 

 especially the anterior pair; other parts yellow but not hairy, 

 in the female the femora are dark and clothed with a few dark 

 hairs. 



The abdomen of the male is yellow and very hairy. In the 

 female yellow-green and not haii-y. The male abdomen is 

 cylindrical, terminating bluntly. There is a dark area on the 

 ventral surface of the fifth segment marking the entrance to the 

 male genital atrium. In the female it is short, broad at the base 

 and conical, becoming more or less oval when gravid. 



The female is smaller than the male and darker, owing to the 

 absence of the yellow hairs. The legs of both sexes are bristly 

 and the pulvilli well developed. 



The sexes are distinguished by the size, difierence in colour, 

 shape of the abdomen, and the black area on the ventral surface of 

 the abdomen of the male. 



There are nineteen British species of the genus, but I have 

 never observed any other breeding in dung. 



S. merdaria is the nearest related species, but is distinguished 

 by both sexes being dirty green in colour and bv there being only 

 two rows of dorso-central bristles on the thorax. 



>S'. scyhalaria is distinguished by the colour of the third antennal 

 joint, which is reddish brown. 



Scato'pliaga stercoraria is widely distributed. It occurs as far 

 north as Nova Zembla, and Siberia, and as far south as JSTorth 

 and South Africa and the Canary Islands. It is common 

 throughout Eiiiope and is found in Asia Minor. I have seen no 

 mention of it occurring in India or Australia. 



It is evidently both a temperate and sub-tropical species. 



