AMERICAN MUSEUM GUIDE LEAFLETS 

RELATIVES OF THE FILTH FLY 
There are a number of other flies sometimes found in houses 
which may be mistaken for the Filth Fly, and the characteristics of 
a few of them may be briefly described. 
Homalomyia canicularis is often supposed to be a “‘young house 
fly.’ It does look like a small edition of the more common and 
dangerous insect; but it is a wholly different species. No insect grows 
after it has attained to the dignity of wings. The wing-veins of 
Homalomyia run without a sharp bend to the margin of the wing. 
This creature is really not even a muscid; it belongs to the Anthomy- 
ide. It breeds in waste organic matter such as manure. 
Muscina is a muscid ge- 
nus. Our species may be 
recognized by the fact 
that they are black flies 
a _— and not shining; the me- 
at ee dian stripe on the thorax 
is light, the fourth longi- 
tudinal vein is only slightly 
bent and the first posterior 
AY: Csmer. cell is scarcely contracted 
at the margin; the hind 
end of the thorax may be 
reddish. MW. stabulans has 
the legs and palpi more or less yellowish, while those of W. assimilis 
are wholly black. The larve feed on excrement and a variety of 
decaying substances including fungi and vegetables. 
Pollenia rudis is known as the “‘cluster fly’’ from the habit which 
the adults have of congregating in masses, especially about the ceilings 
of rooms, when they are looking for a place in which to hibernate. 
When mashed, these flies are very Sreasy and have an odor which 
has been described by some as like honey and by others as “very 
disagreeable.”’ They breed, as parasites, in earthworms. The thorax 
has no distinct stripes and is usually covered with a yellowish ““dust’’; 
the space between the eyes is white, the fourth longitudinal vein is 
sharply bent. | 
The genus Lucilia includes the “‘Sreen- and blue-bottle flies.”’ 
Both the thorax and abdomen are bright and metallic. This descrip- 
tion would apply also to certain other Muscide, but it has not been 

Fig. 5. THE ELE BOUSE FLY 
(Homalomyta canicularts) 
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