y$ Q . 2. ] A paper by the late Br. E. Becker. 79 



the margin. The alulae are large and bluntly lancet-shaped ; the valvse 

 are very large, in colour grey with yellowish margin. 



Legs black 5 femora of greyish hue; femur of the front leg, on the 

 outer side thickly covered with short hairs, on the inner side, both above 

 and below, with rows of long bristles, the upper ones being less closely 

 set than the lower ones ; the femora of the middle and hind pairs of legs 

 are thickly covered with hair, and also have a few large bristles. Tibia?, 

 besides short hairs, have some scattered bristles, which are most numer- 

 ous in the hind pair of legs; in the middle pair of legs the tibia 

 has two spine-like bristles at its extremity. Tarsi are covered with 

 bristles; metatarsus is almost as long as the rest of the tarsal joints 

 together, terminal tarsal joint is club-shaped ; the male has large pulvelli, 

 the female smaller ones ; the claws are long and powerful, and have long 

 slender bristles between them. 



Length of body, in specimens taken from Bomhyx forlunatus (or 

 Besi), ranges in the male from 10 - 5 to 12 millimetres, and in the female 

 from 8*5 to 11 millimetres : while in the specimens taken from Attacus 

 ricini the length ranges in the male from 12 to" 13*5 millimetres and in 

 the female from 11 to 12 millimetres. 



The flies taken from Maldah specimens of Bomhyx fortunatus and 

 also those from Dinajpore specimens of Attacus ricini belong to the same 

 species; they differ from each other in their size, which depends on 

 that of the host, and in the yellow colour, on the heads of the males 

 taken from Attacus ricini being somewhat brighter than in the males from 

 Bomhyx fortunatus. Trycolyga hombycis is distinct from the dipterous 

 parasite Tachina oudji, Guerin (Comptes Rendus, LXX, 1870, p. 844) 

 = Udschimyia sericarm, Rondani (Cornalia, Bull Soc. Entom. Ital., II, 

 1870, p. 137), which attacks the silk-worm Bomhyx mori in Japan : the 

 two species may be distinguished by the fact that in Trycolyga hombycis 

 the eyes are thickly covered with hair, and the abdomen is longer and 

 more slender than in the Japan species. Trycolyga hombycis is very 

 closely allied to the parasite Exorista leucanice, Kirk. var. cecropia, Riley 

 (Ann. Rep. on the nox. benef. Insects of Missouri, II, p. 50), which 

 attacks the American silk- worms Attacus cecropim and A. polypkemus. 

 About the latter parasite Riley writes (loc. cit. IV, p. 108, 1872) — 



" The larvse of this Tachina fly, which is also parasitic on the Cecropia worm, seem 

 to produce an undue and unnatural growth of their victim. In the beginning o£ 

 September 1866 I received an enormous Cecropia worm. It measured over 4 

 inches, was a full inch in diameter and weighed nearly 2 ounces, but, like many 

 other large specimens which I have seen since, it was covered with small oval opaque* 

 white egg shells, clusters of four or five occurring on the back of each segment, in- 

 variably deposited in a transverse direction. The skin of the worm was black where 

 the young parasites had hatched and penetrated. This large worm soon died and 

 rotted, and in about twelve days a host of maggots gnawed their way through the 

 putrid skin. These maggots averaged about one half, inch in length, and in form 



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