PARASITES OF THE JOINT-WORM. 557 



the bottom of the shank and the contiguous part of the 

 foot. The length of the body is ten hundredths of an 

 inch, being somewhat less than that of the JSurytoma. 



From my samples of the straw I have obtained another 

 and a different parasite, belonging to the same family, but 

 to the genus Torymus. The specimen is a female, and, 

 like others of the same genus, it is provided with an ex- 

 serted slender piercer, nearly as long as its own body. 

 The latter is about as long as that of the Pteromalus above 

 described, and is of a deep black color, slightly tinged 

 with green on the face and thorax, both of which are 

 rough and opaque, while the hind body is smooth and pol- 

 ished. The fore wings have an elongated cloudy spot 

 near the middle, and the oblique branch is very short. 

 The thighs, claws, and the antennae except the basal joint, 

 are blackish, the other parts of the legs and the base of 

 the antennas are pale yellow. The hindmost thighs are 

 much thicker than the others, and are notched beneath the 

 end. The eyes have a dull reddish tinge, perhaps not 

 their true color in life. Professor Cabell has sent to me 

 some specimens of this Torymus, including a male, which 

 differs from the female in having all the joints of the an- 

 tennas black. 



The ravages of the joint-worm in the wheat-fields of 

 Virginia are said to have been first observed in Albemarle 

 County, about four or five years ago. They have alarmingly 

 increased from year to year, and have extended over many 

 parts of the adjacent counties, becoming more aggravated 

 each time that they are renewed in the same place. The 

 loss occasioned thereby often amounts to one third of the 

 average crop, and is sometimes much greater ; and during 

 the present season, " some farmers did not reap as much 

 as they sowed." These statements are made chiefly on 

 the authority of Professor J. L. Cabell, of the University 

 of Virginia, who has given some attention to the natural 

 history of the joint-worm, and has recently communicated 



