58 



MOSQUITOES. 



possesses very little consistence ; the mouth is in form of a trunk, 

 and is only adapted to sucking ; their legs are generally long and 

 slender; and the abdomen is more or less pedunculated. 



15. The dip'teras experience complete metamorphosis. The 

 larvae are apodous, and their head is soft and variable ; their 

 mouth is commonly furnished with two hooks. In most of them 

 it is the skin of the larva, which, by becoming hard, serves as a 

 cocoon for the nympha, and then puts on the appearance of a 

 seed or egg. 



This division is very numerous both in genera and species ; 

 besides a great many other insects, we place in it mosquitoes, 

 flies, &c. 



16. The mosquitoes Culex (fig- 53) have a long hairy 



body, antenna in form of plumes, and very 

 long legs. The inconvenience and annoy- 

 ance of these insects are well known, par- 

 ticularly in damp, marshy situations, where 

 they are found in the greatest abundance. 

 Voraciously fond of blood, they pursue us 

 everywhere, enter our dwellings, especially 

 in the evening, and announcing their ap- 

 proach by a sharp humming sound, pierce 

 the skin with the bristle-like lancets in their 

 trunk and distil a venomous liquid into the 

 little wound thus made. In the state of 

 larva and nympha, mosquitoes live in water. 

 The larva has on the segment of the abdo- 

 men next to the last a long tube (fig> 54, 2), 

 by means of which it draws from the atmo- 

 sphere the air it requires: the nympha breathes 

 in the same manner, but by means of two 

 tubes placed on the thorax ; it floats on the 

 surface of the water, and, after having finish- 

 ed its metamorphosis, the perfect insect makes 

 use of its nympha slough or cast skin, as a 

 boat, until its legs and wings have acquired 

 sufficient solidity to enable it to walk on the 

 surface of the water, or betake itself to 

 flight ; for, if its body were submerged, as 

 often happens when the wind overturns their 

 frail barks, they would invariably drown. 

 All these metamorphoses occur in the course 

 of three or four weeks : thus, generations are renewed three or 

 four times in the same year. 



15. How are the larvae of dip'terous insects characterized ? 



16. What are the characters of mosquitoes ? What are the characters 

 and habits of their larvsB ? 



Fig. 53. MOSQUITO. 



Fig. 54, 



