IIYMENOPTERA. 441 



joint-worm in the wheat-fields of Virginia, and the remarks 

 by Dr. Fitch on the pccuUar affection of the wh(!at-straw pro- 

 duced by this worm, led me to suspect tliat tlie disease was 

 identical with that wliich had been observed in barley-straw, 

 and that it originated from the same cause. In the article 

 above named. Dr. Fitch appears to have come to the conclu- 

 sion that the disease was produced by some species of Ceci- 

 domyia. He found the disease of the wheat-straw to be situ- 

 ated immediately above the lower joint, in the sheathing 

 base of the leaf, the substance of which, for a distance ex- 

 ceeding half an inch, was much swollen, and was changed 

 to a more solid and wood-like texture, while the surface ex- 

 hibited several long pale spots, slightly elevated like a blister. 

 The hollow of the stem was entirely obliterated, at some 

 parts, by the pressure of the enlarged portion of the sheath, 

 and was hardly visible at others. Each of the blistered spots 

 covered an elongated cavity, containing a footless worm or 

 maggot, about ten hundredths of an inch long, of an oval 

 form, rather more tapering posteriorly than towards the head, 

 and divided by slight constrictions into thirteen segments. 

 The worm was soft, shining, of a uniform milk-white color, 

 with a small V shaped brown line marking the situation of 

 the mouth. " So exactly," remarks Dr. Fitch, '-does this worm 

 in its form and appearance resemble the larvae of the Hessian 

 fly and other species of Cecidomyia which have fallen under 

 my examination, that I entertain no doubt it pertains to the 

 same genus of insects." 



On the 16th of March, 1852, F. G. Ruifin, Esq., of Shad- 

 well, Virginia, the editor of " The Southern Planter," sent to 

 me that paper for July, 1851, containing some account of the 

 joint-worm, and with it a few samples of diseased wheat-straw. 

 A much larger quantity of the straw, soon afterv^'ards received 

 from him, was divided into two unequal portions, the larger 

 of which was sent to Dr. Fitch, in the hope that between us 

 something definite concerning the origin of the disease might 

 be obtained. Upon examining my samples, I found that the 

 disease was not invariably confined to the sheathing base of 

 the leaf, but that, in many cases, it was seated in the joint 

 56 



