DIPTERA. 137 
It is commonly stated that these flies produce but one or two young, 
but Dr. Curtice is authority for the statement that the sheep tick may 
produce from five to eight young, one after another, which would make 
the multiplication more rapid, and better account for the occasional 
abundance of this pest. 
THE BrrRD TICKS. 
The species occurring on birds are included in the genera Olfersia 
and Ornithomyia, the former being distinguished by the absence of 
ocelli and the presence of two teeth under each claw. 
Olfersia americana Leach is a rather common species on owls and 
other raptorial birds and also the partridge or ruffed grouse. It is 
described and figured by Packard as Hippobosea bubonis, in the Guide, 
p. 433. 
O. albipennis occurs somewhat commonly on herons, and ardee is 
recorded from the same class of birds. Other species listed by Ostén 
Sacken are brunnea, mexicana, propinqua, and suleifrons. 
Ornithomyia contains eight species, of which nebulosa is recorded 
from an owl, Strix nebulosa; and pallida Say from Sylvia sialis. 
THE DEER TICK. 
(Lipoptena depressa Say.) 
This interesting form was described by Say from specimens taken 
from the common deer (Cervus virginianus). It is wingless, as usually 
found on this host, but according to Williston is provided with wings 
and occurs on birds during the early period of its existence. At this 
time the wings are weak, the veins slender. 
THE FOREST FLY oR HORSE TICK. 
(Hippobosca equina Linn.) 
Linneus described this species in 1761, but it must have been a 
familiar form to observers of insects long prior to that date. Since 
then it has received frequent 
notice, and mention of it occurs 
in numerous general works and 
in all treatises on Diptera or on 
the parasites of the horse. 
Its injuries consist in the irri- 
tation produced by the move- 
ments among the hairs, their 
punctures of the skin, and loss 
of blood occasioned when occur- 
ring in numbers. 
It would seem to be far less 
common in this country than in the Old World, and | have yet to hear 
Fia. 73.—Hippobosca equina (copied from Packard). 
