35 2 
The Two-winged Flies 
is a yellowish winged species common on owls, some hawks, and the ruffed 
grouse. Swallows are often infested, and I have taken bird-ticks from half 
a dozen other kinds of birds. A careful search for these curious insects 
will certainly make known numerous new species. 
Fig. 501.—A horse-tick or forest-fly, Hippobosca equina. (After Lugger; natural 
length | to J inch.) 
The genus Lipoptena includes a few known species found on mammals 
which are winged for awhile, but later cast or bite off the wings. They 
probably fly about in their search for a host, after finding which they remove 
their wings and remain for the rest of their life on this host individual. Lip¬ 
optena, cervi is a species found on deer. 
Fig. 502. Fig. 503. Fig. 503. Bat-tick, Nycteribia sp. 
Fig. 502. —Sheep-tick, Melophagus ovinus. Nat. size | in. 
Fig. 504.—A bee-louse, Braula sp. (After Sharp; much enlarged.) 
The bat-ticks, Nycteribiidae (Fig. 503) , are curious long-legged, wingless^ 
small spider-like creatures about \ inch long or less, which look as if the 
