DIPTERA. 435 



the field, while others are carried away when the grain is harvested. 

 When the barley is threshed, numerous small pieces of diseased 

 straw, too hard to be broken by the flail, will be found among tlie 

 grain. Some of these may be separated by the winnowing ma- 

 chine, but many others are too large and heavy to be winnowed 

 out, and remain with the grain, from which they can only be re- 

 moved by the slow process of picking them out by hand. 



In the winter of 1829, Cheever Newhall, Esq. furnished me 

 with a few pieces of diseased barley straw, each of which con- 

 tained several, small, whitish maggots. Since that time this af- 

 fection of the barley has not again fallen under my notice, though 

 I have reason to think that it continues to prevail in many parts 

 of Massachusetts. The following account of my observations on 

 the insects in the barley straw was published in the " New Eng- 

 land Farmer," * in July, 1830. Each maggot was imbedded in 

 the thickened and solid substance of the stem, in a little longitudi- 

 nal hollow, of the shape of its own body ; and its presence was 

 known by an oblong swelling upon the surface. In some pieces 

 of straw the swellings were so numerous as greatly to disfigure 

 the stem, the circulation in which must have been very tnuch 

 checked if not destroyed. Early in the following spring these 

 maggots entered the pupa or chrysalis state, and on the fifteenth 

 of June the perfected insects began to make their escape through 

 minute perforations in the straw, which they gnawed for this pur- 

 pose. Seven of these little holes were counted in a piece of 

 straw only half an inch in length. The insects continued to re- 

 lease themselves from their confinement till the fifth of July, after 

 which no more were seen. Much to my surprise they proved 

 to be minute, four-winged Ichneumon-flies, which are parasitical, 

 or prey, in the larva state, on the bodies of other insects. I 

 had hoped tojiave obtained the true culprits, the cause of the 

 disease, supposing that the latter were allied to the Hessian fly ; 

 but these little insects, while in the larva state, had destroyed 

 them all, and, having finished their appointed task, and undergone 

 their tranformations, now made their escape from the straw in the 

 winged form. The scientific name, given to this newly dis- 



Vol. IX. 



