32 MASS. EXPERIMENT STATION BULLETIN 157. 



Following the withdrawal of the ovipositor, she backs up, and, applying 

 her proboscis to the aperture previously made, feeds on the juices of the 

 tissue thus exposed, protruding and retractirg her ovipositor several 

 times wliile so engaged. Towards the last of the feeding the proboscis is 

 applied intermittently. The blind end of the incision made is almost in- 

 variably directed towards the apex of the leaf or leaf -lobe. 



The length of time spent in the process varies. A large number of 

 observations showed a variation of from twenty to one hundred and forty 

 seconds for the piercing and cutting operation, although the more usual 

 was from thirty to sixty seconds, and a variation of from six to one hundred 

 and twenty-nine seconds for actual feeding, the more usual period being 

 from about twenty to forty seconds. 



The immediate apparent effect of the piercing of the epidermis by the 

 female and her subsequent cutting directly beneath it is a very small, pale 

 and usually fan-shaped blotch with a minute aperture in its periphery at 

 the point where the handle of the fan would be located. This blotch, 

 which measures roughly from ^ to f millimeter by I to nearly 1 millimeter, 

 but usually 2 by f millimeter, represents the area of the epidermis cut 

 away from the parenchyma. Its paleness, which contrasts with the 

 green color of the rest of the leaf surface, is due to the maceration or de- 

 struction of the green chlorophyUous tissue benea h, which imparts the 

 green color to the colorless and closely applied overlying epidermis. 



As pointed out once before, these blotches, with the exception of a few, 

 do not retain their blotch-like appearance. Reacting to the injury, the 

 leaf tissue at that point is stimulated to new growth, and, growing out- 

 wardly, away from the center, gradually undergrows the elastic epidermal 

 area or blotch and raises it above iis normal level, forming a wart-like 

 tubercle or papilla with a single perforation at a point in its periphery. 

 (Plate II., Fig. 9.) On the other host plants under observation in the 

 insectary these papillie formed less readily and less perfectly. 



Feeding is done to a greater extent from the upper surface of the leaf. 



Do the males feed upon the juices of the leaf tissue of the host plants as 

 do the females? 



Lacking the ovipositor with which the females are provided, the males 

 are of course unable to pierce the epidermis of the leaf. In order, there- 

 fore, to feed upon the juices of the leaf tissue they must resort to the 

 punctures made by the females. This, it should be said, the vso-iter has 

 not observed them doing. Experimental evidence, however, as will be 

 seen below, though somewhat contradictory, would seem to indicate that 

 they do. 



Thus males live longer when confined with females upon leaves on 

 plants which are pierced by the females for feeding purposes than when 

 isolated by themselves, under the same conditions, on leaves which remain 

 entire on account of the inability of the males to pierce them. The length 

 of life of a large number of males isolated by themselves on leaves within 



