LIFE HISTORY 
41 
Hibernation 
The typhoid fly apparently suddenly disappears with 
the first sharp frost. It will reappear later on the 
warmest days. With a great reduction of the tem¬ 
perature of their breeding places, many larvae are killed, 
and eggs as well. Whether the pupae in their tight 
puparia are destroyed by a certain degree of cold does 
not seem to be known. The adult flies undoubtedly 
linger in warmed houses throughout the winter, but 
that enough of them remain in active condition in such 
locations to perpetuate the species and to start the rap¬ 
idly multiplying generations of the following summer 
seems doubtful. The adult flies undoubtedly remain 
dormant even in warmed dwellings, and it is altogether 
likely that some of them remain dormant throughout 
the winter months in sheltered but cold situations. 
Many adult insects pass the winter in this way, and 
observations have been made which indicate that this 
is the case with the house fly, although as a matter of 
fact sufficient attention has not been paid in the obser¬ 
vations on record of the exact specific identity of the 
flies in question. As has been pointed out before, there 
are so many species of flies which so exactly resemble 
the typhoid fly to the macroscopic eye that any one 
may be pardoned for stating that house flies have been 
seen tucked away carefully in cracks, when a micro¬ 
scopic examination would have shown that some other 
species was concerned. 
The best observations on this general subject which 
