1912] Stomoxys Calcitrans Linn. 423 
These are situated on the broad end of the body and are close together, 
comparatively large, and circular except for the inside edges, which 
are straight. Under favorable conditions the larva is full grown and 
pupates in from 4 to 7 days. (See Fig. 2). 
Pupa: Yellowish brown to dark reddish brown, barrel shaped, but 
tapering slightly towards the anterior end, 6 to 8 mm. long. (See 
Fig. 3.) Under most favorable conditions of temperature and humidity 
the pupal stage lasts 3 to 5 days. 
Adult: The normal length is about 6 or 7 mm., mouse gray in color, 
while the thorax has four black, longitudinal stripes, which are usually 
most sharply defined in front. It may be noticed that the compound 
eyes more nearly meet on top of the head in the male than in the female. 
The proboscis, at rest, is not visible from above. The end of the 4th 
longitudinal vein bends sharply up so as to nearly join the vein above it. 
(See Fig. 1.) Females hibernate in winter. The House-Fly cannot 
bite and does not suck blood. 
Homalomyia canicularis, Linn. The Lesser House-Fly. 
Egg: This has not been studied by the writer but it is reported to 
be deposited in decaying animal and vegetable matter. 
Larva: About 8 mm. long when full grown, brownish yellow in 
color and somewhat abruptly narrowed in front. This larva may 
readily be distinguished from that of Musca domestica or of Stomoxys 
calcitrans by the presence of spines shown in Fig. 5. ~ 
Pupa: The bristles of the last larval stage still persist in the pupa 
as does also the brownish coloration. The case is, however, somewhat 
shorter than the extended larva. (See Fig. 6.) 
Adult: Normal length about 6 mm., but this fly is much more 
slender than the common house-fly. The thorax is blackish or dull grey, 
but the distinct longitudinal stripes are not noticeable in the <. 
Front of head shining white in the o’, while that of the 2 is darkish 
grey. Width of vertex in the o is one-seventh; in the 2 one-third the 
total width of the head. The proboscis is not visible from above. End of 
4th longitudinal vein not bent up towards the vein above but parallel . to 
it. When this fly is at rest the tips of the wings are nearer together than 
in Musca domestica. This adds to the narrower and smaller appearance 
of the insect, and no doubt accounts, in some degree, for the common, 
but erroneous idea that these are young house-flies. Like the house-fly 
this species cannot bite and does not suck blood. 
Stomoxys calcitrans Linn. The Stable Fly. 
Egg: About 1 mm. long, white, elongate and banana-like in shape. 
One side straight, with a deep groove, the other curved. Laid in small 
masses of 40 to 70, in accumulation of moist and fermenting vegetable 
matter (straw, etc.), or in fresh horse manure. At favorable temper- 
ature the eggs hatch in 2 to 4 days. 
Larva: Length when full grown about 10 mm., very similar in 
appearance and color to the larva of Musca domestica, but may be read- 
ily distinguished by the plates of the respiratory tubes which are “dis- 
