300 NORTH AMERICAN INSECTS. 



because the latter deposits its eggs in the body of the horse, 

 while the larvae or maggots of the former, as well as their 

 pupae, are plentifully found in the ground, in meadows and 

 near ditches. 



Dr. Harris mentions three species of horse-fly, viz. : The 

 Black Horse-fly {Tdbanus 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 Belted Horse-fly {Tahanus cincius) is smaller, of 

 an orange color, and is not as common in the States. 



The Lined Horse-fly (Tahanus 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 House-fly (Musca domestica) is well knowni 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 



