FAMILY TIPULID.E. 173 



It is scarcely necessary to say that many of the. diptera, though small in size, are great 

 annoyances to man and animals : the cpstridcv are perpetual torments to our domestic ani- 

 mals ; and musquitoes, in the warmer regions especially, are so troublesome as to require 

 special means of protection from their stings. 



The transformations in this order are incomplete. The larva; are white and fleshy, cy 

 lindric, and without feet : they are usually called maggots. 



Tipulidae. 



Genus CECIDOMYIA. 



It is a very curious fact in natural history, that the most serious injuries the crops of the 

 husbandman receive are inflicted by insects the most minute and insignificant in size : the 

 very weakest among the tribes of animals are the greatest destroyers of the products of 

 man's industry. The whirlwind or the hailstorm, it is true, sometimes sweeps over his fields 

 of wheat and corn, or a flood of water may pass over them, and leave desolation in its 

 track ; but these terrific visitants are harmless in comparison to the tiny fly that sports 

 and dances over his grain-fields. With all our wisdom, we have not yet devised a weapon 

 to extirpate this foe, nor a defence to secure us from its ravages : our most successful 

 efforts have been but failures ; and were it not for the aid of the elements, or the secret 

 influence of an unseen but benignant hand, the foe would maintain the field in the face of 

 him who has subjected to his will the proud warhorse and the colossal elephant. 



Cecidomyia is the generic name of these destroyers : they are flies, each with two wings, 

 antenna?, poisers, etc. Several species have been described, one of the most prominent of 

 which is the C. destructor of Say, the hessian fly. The genus is characterized by the joints 

 of the antenna? being variable from fourteen to seventeen : the form of the joints in the 

 female also differ from their form in the male ; the former being oval, and the latter glo- 

 bular, but both are furnished with hairs issuing from the joints in the form of a whorl 

 (See Plate iv, fig. 1). Wings three-nerved, ciliate or fringed : joints of the tarsus short. 



Cecidomyia Hestructor. Hessian-fly. ( Plate iv.) 



This species is black, except that the abdomen is only tawny, though each ring is more or 

 less black : legs pale red or brownish, with black feet. Length of the body one-tenth 

 of an inch : the expansion of wing rather exceeds the length of the fly. See fig. 1 c, 

 which represents the natural size of the Cecidomyia destructor. 

 The hessian-fly has occasioned as much controversy as any species in the insect kingdom. 

 I published in the American Journal of Science in 1846 - 47 an article furnished by Dr. 

 Fitch, which contains all the important facts in its history. I deem it, therefore, unneces- 

 sary here to go over all of the ground occupied by that paper. 



