CHAPTER XIX 
OTHER INSECTS OF SPECIAL INTEREST 
Flies are the commonest insects we have, there being hun- 
dreds of different kinds of them. Tiny flies and gnats never 
grow larger, but all the different sizes and forms that we see 
are different species. Besides the house fly we may mention 
the stable fly, which we. often see in great numbers around 
horses and cattle. It resembles the house fly, but it bites 
quite viciously, while the house fly does not. The blow 
fly or bluebottle fly is another kind that is of special inter- 
est. If we put a piece of fresh meat or fish where these flies 
can get at it, they are apt to lay masses of their whitish yellow 
eggs upon it. 
But of all the different species the common house fly is by 
far the most important, and we must therefore consider it 
at greater length. Until recently most people have regarded 
house flies as merely a nuisance, but we have now learned 
that they are a constant menace to health. They may walk 
through any filth in the neighborhood and the next minute 
wipe their feet on the food we are about to eat and spread 
upon it not only filth but also the germs of typhoid fever, con- 
sumption, and other diseases. We have therefore adopted 
the slogan, ‘‘ Swat the Fly,” and practice it with more or 
less diligence in our homes, but it is easier as well as wiser 
to prevent their multiplication than to kill the flies after they 
are produced. 
Only very few flies live through the winter, and when these 
221 
