THE COMMON HOUSE-FLY. 149 
will appear later. As soon as the nights become cool, flies 
try their very best to find shelters for the winter, and no 
matter how carefully we may protect doors and windows 
with screens they will find an entrance, to the great worry 
of our better halves. Sufficient numbers would thus find a 
shelter and survive the rigors of a northern winter, if they 
did not bring with them at the same time an enemy they can 
not escape, and one that will kill the very great majority of 
all house-flies at that season. Only a few escape this 
“slaughter of the innocents,’’ and these few are the ones that 
may be seen during the winter in our houses; others will 
find wintering quarters under rubbish, and remain in a 
torpid condition until the warm weather of spring coaxes 
them back to life. Most flies that escape death in autumn 
hibernate in their winged form; a few may also winter over 
as pupe, though this is doubtful, at least in Minnesota. 
“Have you ever observed a genuine house-fly, one with a 
full pedigree? This questionseems absurd, but the writer’s ex- 
perience has been that really few persons can tell the difference 
between a house-fly and other flies so common in our houses. 
All flies found upon our walls, upon windows and tables, 
are called house-flies, yet at least a dozen species are mixed 
up in that congregation, all widely different, more so than 
cows and horses. One of the most curious habits of the 
genuine Simon-pure house-fly is its peculiar position during 
sleep, and once observed it will always be recollected. When 
we enter a dark room all flies are sleeping, but only the 
house-flies sleep with their heads downwards, the others in 
a more normal position. By bringing a light into theroom, 
you may ascertain very rapidly the proportion of true 
house-flies to that of other intruders. Notwithstanding our 
intimacy with the fly, or rather its intimacy with us, how 
very little is really known of it by the plurality of tormented 
humanity! Those present always excepted, not ten per cent 
of our fellow citizens ever know how many legs or wings a 
fly has or where it spends its early days in infantile sports. 
How many know why it so suddenly appears in countless 
numbers to torment the masterpiece of creation, not caring 
a straw when or where it attacks him? The ministers in 
