THE CANADIAN ENTOMOLOGIST. 95 



made by various species of Homoptera affecting the same plants, and tlie 

 conclusion that these insects are responsible for a part at least of this 

 injury seems to me to be very strongly suggested, though not demon- 

 strated. 



There is no question whatever that these Homoptera puncture grass, 

 both blades and stems, to procure their food. This is shown by the 

 numerous punctures and deadened spots on the leaves and stems, and 

 can be verified by watching the insect itself That the puncture of the 

 stem just above the joint so as to enter the succulent base of the 

 terminal node, and the extraction of the sap from that part, would cause 

 their shrivelling and the consequent whithering of the node above, seems 

 sufficiently evident. 



Knowing the habits of these insects, and considering the fact of their 

 actual occurrence on the injured plants and the presence of injured spots, 

 such as these insects make in getting their food, there seems to me no 

 reasonable doubt of the possibility of these insects causing all the damage 

 observed. The difficulty, in case we accept this view, is to explain why 

 Silver-top is not more abundant than it is, or that such experiments as 

 that by Mr. Fletcher in caging Hemiptera on grass did not produce it, 

 for these insects swarm on almost every blade of grass. These insects, 

 however, work on leaves and stems all the way from the surface of the 

 ground to the tip, and their punctures are distributed promiscuously over 

 all their surfaces. In stiff leaves and sheaths as well as in the stems 

 above the succulent basal portion the shrivelling is confined to the few 

 cells immediately surrounding the puncture, but in case the beak is 

 thrust into the succulent part the effect is to kill the cells of an area 

 through which all the sap for the nourishment of the upper node must 

 pass, and, hence, the more conspicuous effect. 



Some of my observations, moreover, show that this injury is not con- 

 fined entirely to the upper joint, though always most conspicuous in the 

 whitened head, but I have found the stem affected in lower nodes, and 

 in some cases almost to the ground, in which cases also some of the 

 upper leaves show the whitening effect of the injury. 



The species of Homoptera most likely to be concerned in this work, 

 are the common species of Deltocephalus, especially inimicus debilis, etc., 

 which are serious grass pests, in any case, from their attacks upon the 

 stems and leaves, and which I have recorded in some detail in a recent 

 report to the Division of Entomology. 



