67 
Genus 
MELOPHAGUS, Latreille. 
Melophagus ovinus, Linn. 
The Sheep " Tick," Sheep " Louse," or Keel. 
Plate 34, Fig. 2. 
A higher degree of adaptation to a parasitic existence is exhibited 
by this species than by any of the foregoing members of the Family 
to which it belongs, since the wings are always entirely wanting in 
both sexes. This peculiarity, coupled with the general strangeness 
of its appearance, which presents little resemblance to an ordinary fly, 
and the fact that it passes its whole life-cycle in the wool of the sheep, 
has gained for the insect two of the popular names mentioned above. 
The late Miss Ormerod (' Report of the Observations of Injurious 
Insects and Common Farm Pests, during the year 1895 ' (London : 
Simpkin, Marshall, Hamilton, Kent & Co., Ltd., 1896), p. 120) states 
that " when seen in the wool " Sheep Ticks " greatly resemble small 
spiders," though, of course, the presence of only three pairs of legs is- 
sufficient to show that the creatures must be insects. The Sheep Tick 
does not possess the activity of the Forest Fly, but moves quite slowly 
and quietly through the wool of the host, to which, when not in 
excessive numbers, it may cause little annoyance. Dr. Parry, however 
(quoted by Youatt in 'The Mountain Shepherd's Manual' (1862), 
p. 35), says that Alclopliagus ovinus " is extremely injurious to sheep, 
by making the animal bite and rub itself, so as not only to hurt the 
fleece, but to break the skin, in consequence of which the fly [Lucilia 
sericata, Mg.] is apt to fix on the wool near the wounded spot and 
there deposit its eggs." 
The Sheep Ticks in the Museum collection were taken during May 
and Tune, i.e., at shearing-time, but Curtis believes that the insect is to 
