300 © NORTH AMERICAN INSECTS. 
because the latter deposits its eggs in the body of the horse, 
while the larve or maggots of the former, as well as their 
pupz, are plentifully found in the ground, in meadows and 
near ditches. 
Dr. Harris mentions three species of horse-fly, viz.: The 
Brack Horse-riy (Tabanus atratus), the body of which is 
black, and its back covered with a whitish bloom, like a 
plum. This fly is almost an inch long, has very large 
wings, as well as very large, bluish-black, shining eyes, 
and is found commonly throughout the United States. 
The Berrep Horse-Fiy (Zabanus cinctus) is smaller, of 
an orange color, and is not as common in the States. 
The Linep Horse-rry (Tabanus lineatus) is still much 
smaller, and has a whitish line along the top of the hind 
body, and is very common. 
There are many other species of this blood-thirsty genus, 
but most of them are smaller, and comparatively uninter- 
esting; and as this order of insects has had the least atten- 
tion from naturalists, there are very few facts known as yet 
regarding their life and history. We trust, however, that 
the zealous entomologist, Baron Osten Sachen, of the Rus- 
sian Legation at Washington, will soon favor us with a vol- 
ume on North American Diptera, which he has for several 
years made a principal study, and of which we are sadly in 
want. 
The Hovser-rry (Musca domestica) is well known to every 
one as an insect about three lines long, which has a dark- 
brown thorax with four black lines, a dark-brown hind 
body spotted with black. The eyes are reddish-brown. 
Between the claws there is a small round ball, from which, 
when pressed, there issues a glutinous fluid, which enables 
the fly to run upon smooth surfaces, such as mirrors, win- 
dows, ceilings, etc., which hence become covered with dirty 
