1909. | ECTOPARASITES OF THE RED GROUSE. 321 
B. Diprera.—F lies. 
a.) Fam. Hippoboscide. 
TIl.—OrayrHomyra LAGoPopIs 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 
O. lagopodis:—It is “smaller than O. 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 verv large area of smoky colour on each side. Mr. Collin has 
pointed out that the segments, or abscissze, of the costa afford a 
good character ; the relative lengths of the outer two being in 
O. lagopodis as 9-8, and in O. avicularia about 12 or 123-8. 
The bristles on the scutellum are usually more numerous, as well 
as larger, in O. avicularia.” Recently a second species, O. frin- 
gillina Bezzi, has been separated off from the O. 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 antennz 
apparently of two joints, ending in four hairs, of which one is 
far longer than the others; other symmetrically arranged hairs 
are shown in Pl. XLIV. fig. 22. In the middle line is the 
proboscis; this consists of two lateral, movable, palp-like struc- 
tures, each bearing hairs and terminating in a stout bristle. 
These structures are presumably the maxillary palps. Then there 
is a median very mobile structure, which is the sucking-tube ; 
this moves in all planes, and may be protruded or withdrawn. 
Tits mouth shows a somewhat plicated orifice, and behind it 
undoubtedly endsin a sucking pharynx. This median structure 
is probably homologous with the second maxille or the labium. 
The feet of the grouse-fly are large but very beautiful. In 
Pl. XLIV. fig. 23, we show the outer surface of one of the feet, 
and the same figure shows part of the femur, the tibia, and the 
five joints of the tarsus, the fifth being by far the largest. 
* Ent. Monthly Mag. II. ser. xviii. 1907, p. 58. 
