256 QUARTERLY JOURNAL. 



will be very liable to consider a number of insects to be cecido-' 

 myiffi, which in reality belong to some of its kindred genera. 



The genus cecidomyia belongs to the order diptera, of system- 

 atic works. This order includes all those insects which have bat 

 two wings, and which are known in our common language by the 

 names " flies" and " musketoes." Gnats, midges, and some other 

 names, are given locally to some of these insects, but are not irti 

 general use in our country, and consequently convey no definite' 

 ideas to the great mass of our citizens. 



All the insects of this order undergo what is termed a perfect^ 

 metamorphosis— their eggs hatching to footless larvce^ commonly 

 called maggots or grubs, and these having attained their full growth 

 change to pupce, in which state many of them resemble a seed or 

 an egg, and some surround themselves with a kind of silk-like 

 cocoon. From these pupse the perfectly formed and fully grown 

 flies eventually come out. 



A laro-e number of the insects of this order are obnoxious to man 

 in a variety of ways. Some suck his blood, their poisoned wounds 

 producing pain, succeeded by an itching and swelling of the part. 

 Some teaze and torment him, by pertinaciously alighting upon the 

 uncovered parts of his body,' or swarming upon the viands spread 

 upon his table. Others deposit their eggs upon his domestic ani- 

 mals, that their larvee may live upon or within their bodies ; as, 

 the horse-fly, bot-fly, sheep-fly, ox-fly. Others still, produce larvffi 

 which injure vegetation to a greater or less extent ; as, the radish- 

 fly, onion-fly, cabbage-fly, pear-flies, fruit-flies. But, as if to coun- 

 terbalance for these pests, this order also furnishes many species 

 which render us special services, by feeding upon and destroying 

 noxious species — by devouring putrid animal and vegetable sub- 

 stances, which might otherwise poison the air we breathe, &c. 

 How forcibly do such facts portray the importance of our becom- 

 ing acquainted with this class of beings, that we may know which 

 are our friends and which are our foes — which to cherish and which 

 to destroy. 



Of the several family groups comprised in this order, the genus 

 under consideration pertains to that named Tipulidje, being com- 

 posed of those insects originally embraced by Linnaus in his ge- 

 nus Tipula, a name in use among the ancients to designate some 

 kind of water-spider, and not inappropriately bestowed upon these 



