HISTORY OF INSECTS. O 



frequented by the larva, and in this it shortly changes to a 

 pupa in an upright position : the case being always open at 

 top, the head and shoulders of the pupa are seen projecting 

 above it. The pupa much resembles that of a moth : it is 

 perfectly motionless, of a brown colour, and exhibits very 

 distinctly the parts of the perfect insect through its skin : 

 from the back of its head arise, on each side, four hair-like 

 appendages ; these are tubular, and appear to be designed 

 for breathing. About the sixth of July the little creature 

 bursts from its sheath ; the case of the chrysalis opens in a 

 right line down the back, and the perfect insect emerges 

 through the opening, surrounded by a bubble of air, and 

 slowly begins to unfold its wings under the water ; finally, 

 its skin being cast, and maturity attained, the imago dis- 

 engages itself from its former habitation, and mounts within 

 its bubble to the surface of the water, when the bubble 

 bursts, and the creature, with its new organs, has acquired 

 a new element. The imago is a small black 

 fly, with two large transparent wings, which, 

 when at rest, repose horizontally on its back ; 

 moderately long legs, and short stout anten- 

 nae : it flies with ease, and somewhat sportively, rising and 

 falling. In this country it is found in the damp parts of 

 woods, and other similar situations ; but, happily, in very 

 limited numbers. 



There is scarcely any creature more annoying to men 

 and animals, than this little fly : its attacks are made in in- 

 numerable multitudes, and it is troublesome, not only from 

 the pain and inflammation caused by its bite, but also from 

 the intolerable itching occasioned by its crawling over the 

 skin. In the woody and marshy parts of Lapland, these 

 flies swarm in the months of July and August ; nay, even 

 the summits of the highest mountains, though capped with 

 perpetual snow, impose no obstacle to their progress. 



