75 



WHERE FOUND. 



The time the eggs were deposited that produced these larvae is 

 unknown, and can only be surmised from the time of hatching of 

 the perfect insects and the place in the stalk where the larvae are 

 found. This was inside the culm or stalk, a few inches from the 

 ground, very seldom in the straw between the head and the upper 

 joint, more frequent in the straw below this upper joint, and in the 

 next internode below. They were in the interior of the stalk, usually 

 close to or a little above the joint or node, working in the soft 

 tissue forming the interior, the natural cavity serving in most cases 

 to contain them, but in some instances they gnaw a partial chan- 

 nel to one side of this. Where the stalk is large they may some- 

 times be found completely embedded in the tissue of the stalk, just 

 outside the hollow center, but in such instances they were always 

 pretty close to or in the joint, where the stalk tissue is thickest. 

 Sometimes more than one worm would be found in the same stalk, 

 but in such cases they would be found in different parts of the same 

 internode or in different internodes, it being no uncommon thing to 

 find two internodes infested. In no instance did I find a stalk 

 swollen by their presence, as in the case of stalks infested with 

 Joint-worms (Isosoma Hordei), there being no external indication of 

 the presence of the worm other than a somewhat premature ripen- 

 ing of the grain and less of it in the head. While the natural 

 cavity in the internodes furnished them a retreat often large enough 

 to contain them, the walls of this cavity were considerably gnawed 

 from half an inch to an inch and perhaps more, often almost or 

 quite to the hard exterior. Some stalks appeared to be a little 

 spongy in their interior, as though the presence of the worm had 

 caused an abnormal growth, but an examination of such places 

 with a glass showed that their structure was not different from 

 other portions of the interior of the culm, no additional fiber depos- 

 ited, nor any bending or hardening of that present, it all being 

 continuous with the tissue above. 



The manner in which the injury is done by this worm seems to 

 differ from that of the ordinary Joint-worm more in the way than 

 in the effect. According to Dr. Fitch and others the presence of 

 the worm in the hard tissue of the outside of the stalk, whether of 

 the joint or of the internode, a little removed from the joint, arrests 

 the flow of sap by the hard, knotty gall, but this seems to arrest 

 the flow more from breaking the internal fibers of the internode. In 

 this case there is not so often a breaking down of the stalk as with 

 the Joint-worm, for the erect position of the culm is not interfered 

 with, and the outer or stiff portion remains entire till the perfect in- 

 sect is ready to emerge. The chief influence upon the wheat seenis 

 to be exerted during the later stages of its growth, when the worm is 

 approaching its maturity, as it is then probably a more rapid feeder. 

 As evidence of this, the heads are fully formed, to all appearance, 

 but the grain in them is light, and they ripen prematurely, showing 

 hat the supply of material for the full development of the head has 

 een cut off. 



