ORDER VII.- TWO-WINGED INSECTS, OR FLIES. 305 



occupied more than two hundred sheets of paper. At last 

 Sir Joseph Banks, a distinguished naturalist in England, was 

 applied to for information; but so little was known of ento- 

 mology here that, although whole packages of descriptions 

 were forwarded to him, he could not explain whether the 

 injurious insect was a moth, a bug, or a fly. 



Soon afterward, however, the natural history of the Hes- 

 sian-fly, and the measures necessary to prevent its ravages, 

 became the subject of investigation of several scientific gen- 

 tlemen, among whom were Dr. Isaac Chapman, in the 

 "Memoirs of the Philadelphia Society for the promotion 

 of Agriculture ;" Jonathan N. Havens, Esq., in the "Trans- 

 actions of the Society for promoting Agriculture in New 

 York;" Mr. Herrick, in the "American Journal of Sci- 

 ence;" Mr. Edward Tilghman, of Maryland, in the "Culti- 

 vator;" and, above all, our distinguished naturalist, Thomas 

 Say, in the " Journal of the Academy of Natural History 

 of Philadelphia." From the researches of these distin- 

 guished men we derive the following information : 



The Hessian-fly is very small, and its body and wings are 

 entirely black. The female deposits her eggs on the stalk 

 or leaves of wheat, barley, rye, and Timothy grass, as soon 

 as the plants are up in the spring or fall, the maggots from 

 which enter the stalk and feed upon its substance and sap, 

 thereby weakening the stem and causing it to break and 

 fall before the grain is ripe. The eggs are very diminutive, 

 of a reddish color, and are hatched by the caloric of the at- 

 mosphere, according to the temperature, in one or two 

 weeks. The maggots are also of a reddish color, and as 

 soon as hatched fasten themselves on one of the joints and 

 suck the sap of the stem, until after five or six weeks they 

 attain their full size, and then change into light-brown 

 pupae from which the perfect insect soon emerges. This 

 process takes place at least twice, and sometimes thrice a 

 year, upon the wheat and other grain that grows in spring, 



