358 THE GROUSE IN HEALTH AND IN DISEASE 



a cap which is pushed off when the young emerges. The eggs are laid between the 

 barbules of the vanes or near the bases of the filo plumes, and adhere to their 

 supports by means of some sticky excretion (PI. LIV., Fig. 2). 



The eggs appear to be laid throughout the summer ; the first time we found 

 them (some of them were empty) was on July 2nd, 1907, and we found others 

 later in the season. 



There is no metamorphosis ; the young emerge from the egg-case as small 

 miniatures of their parents. They seem to cast their skin several times ; but 

 the exact number of ecdyses is not known. 



B. DIPTERA. Flies. 



(i.) Fam. Hippoboscidse. 



III. ORNITHOMYIA LAGOPODJS Sharp. 



Till recently it had been thought that the Grouse-fly was the same species as 

 the common bird-fly, Ornithomyia avicularia L. ; but recently Mr D. Sharp : has 

 pointed out that it is a distinct species, which he has described, as follows, under 

 the name of 0. lagopodis (PL LV.) : It is " smaller than 0. avicularia, and 

 distinguished by its peculiar lurid blackish colour, without any trace of green even 

 on its feet or legs ; the rostrum is black, and the hairs of the body and appendages 

 are shorter than in the better-known form ; on each side of the thoracic pleuron, 

 between the front and middle legs, there is a very large dark patch extending as 

 far towards the middle as the base of the front coxa, and divided into two parts by 

 an oblique pallid line. The head is considerably smaller and narrower than that of 

 O. avicularia, and has beneath a very large area of smoky colour on each side. 

 Mr Colin has pointed out that the segments, or abscissae, of the costa afford a good 

 character ; the relative lengths of the outer two being in 0. lagopodis as 9-8, and 

 in 0. avicularia about 12 or 12^-8. The bristles on the scutellum are usually 

 more numerous, as well as larger, in O. avicularia." Recently a second species 

 O. fringillina Bezzi, has been separated off from the 0. avicularia, so that we now 

 have three species of Ornithomyia in this country, and probably more will be 

 added as the group is further studied. Mr Sharp thinks that the same species 

 frequents the Willow-Grouse, L. albus, of Scandinavia. 



The head and mouth-parts of this fly are very interesting. A ventral view 

 shows, between the eyes, the short antennae apparently of two joints, ending in 



1 Entomologists? Monthly Magazine, II., ser. xviii. p. 58, 1907. 



