6 



are winged. Egg-laying by the last generation of adults may 

 continue until snow comes, but only the adults appear to be able to 

 survive the winter. 



INJURIES. 



The amount of injury done by these minute insects is little appre- 

 ciated on account of their small size, but what they lack in this 

 regard is made up by their numbers. Calculating the number of eggs 

 laid by each adult at 50 and allowing each of these on becoming 

 adult to lay 50 more (no males having thus far been discovered, and 

 the probability being that they are rare, if they exist at all) and con- 

 tinuing this rate of increase for the eight generations usual in an 

 ordinary season, we have the astonishing number 781,250,000,000, 

 as the number of descendents in the eighth generation from one 

 insect, while during the single summer which it requires to produce 

 eight generations, not only these, but also all the members of the 

 intervening generations (797,193,877,550 in all) have during a por- 

 tion of their lives been sucking the juices from the grasses of our 

 fields. It should not be forgotten, however, that many individuals 

 fail to reach maturity, thus reducing this estimate. It has also been 

 noted that while the increase appears to be extremely rapid during 

 the early summer months, the heavy showers of midsummer appear 

 to destroy many of the insects. 



FEEDING HABITS. 



"The adults of this species feed entirely upon the leaves and exter- 

 nal parts of the grass. They are very seldom found within the 

 sheath of a leaf, but frequently congregate in numbers within the 

 terminal leaf before it has fully unrolled. They select the fresh 

 tender parts of the grass, and consequently their work is most 

 apparent upon the upper leaves. The mouth parts are used to 

 pierce the surface of the leaf and the wall of a cell below. As soon 

 as the juices contained in this cell have been extracted, the piercing 

 mouth parts are withdrawn and another cell is punctured, the empty 

 cells presenting a shrunken, whitish appearance. The insects usu- 

 ally feed lengthwise of the leaves, their path being marked by whit- 

 ish streaks in the tissue of the leaf and by dots of dark excrementi- 

 tious matter. 



