THE HESSIAN FLY. 571 



represented by Mr. Lesueur, in the plate designed to accom- 

 pany Mr. Say's description of the insect. 



The following brief history of the habits and transfor- 

 mations of the Hessian fly will be found to agree essen- 

 tially with the excellent observations on this insect, written 

 in the year 1797, by Dr. Isaac Chapman, and published 

 in the fifth volume of the u Memoirs of the Philadelphia 

 Society for Promoting Agriculture," and with the more 

 full and equally valuable history of the insect, by Jona- 

 than N. Havens, Esq., contained in the first volume of 

 the " Transactions of the Society for the Promotion of 

 Agriculture, &c, in New York." Mr. Herrick has kindly 

 permitted me to make free use of his valuable account of 

 this insect, contained in the forty-first volume of " The 

 American Journal of Science," and of other information 

 communicated by him to me in various letters. He has 

 spent some time in carefully observing the habits of the 

 fly, during many years in succession, after having fitted 

 himself for the task by the study of the natural history 

 of insects in general. His statements therefore may be 

 relied upon, as in the main correct. Moreover, they are 

 corroborated by the observations of many other persons, 

 published in various works, which have been consulted in 

 the course of my investigations. 



Of this insect, two broods or generations are brought to 

 maturity in the course of a year, and the flies appear in 

 the spring and autumn, but rather earlier in the Southern 

 and Middle States than in New England. The transfor- 

 mations of some in each brood appear to be retarded beyond 

 the usual time, as is found to be the case with many other 

 insects ; so that the life of these individuals, from the egg 

 to the winged state, extends to a year or more in length, 

 whereby the continuation of the species in after years is 

 made more sure. It has frequently been asserted, that the 

 flies lay their eggs on the grain in the ear ; but whether 

 this be true or not, it is certain that they do lay their eggs 



