THE PINE INVESTIGATION. 377 



green worms (the larvae of the clover leaf beetle) which are 

 stripping the clover plant of its leaves and stems. They ap- 

 pear like a vast invading army of insect destroyers against 

 which it appears useless for human effort to contend. Yet 

 within a few days they are all dead over the entire infested 

 area, as if by a blighting wind ; and the clover plant soon re- 

 covers and goes on growing as if nothing had happened. 



This disease appears to follow the beetle wherever it goes ; 

 and so sudden and effectual is its effect, that bu f few of the in- 

 sects escape. These deposit eggs for, another brood which in 

 turn suffers from the disease, and so on. Year after year the 

 disease appears and prevents the total destruction of the clover 

 crop. 



As an example of the action of a similar disease to that of 

 the clover leaf beetle on forest tree caterpillars, I may mention 

 here an interesting observation in Greenbrier county, in July, 

 1893, where on Cranberry Mountain in the midst of a vast 

 hardwood forest, all kinds of trees and shrubs were completely 

 defoliated by a small measuring worm ( Geometrid). Hundreds 

 of dead caterpillars were observed on all sides, clinging to 

 twigs, partly eaten leaves, and the bark of the trees. A few 

 living examples were found and placed in tin boxes for speci- 

 mens and to breed the adult; but all were dead within a few 

 days, and had the characteristic appearance of caterpillars that 

 die from disease. Thus it was evident that the ravages of the 

 insect had been suddenly brought to an end by the disease. 

 The forest growth on one hundred acres or more in one place, 

 had been defoliated by the insects which had apparently spread 

 from central points of infection; so that the sudden disappear- 

 ance of the caterpillars left a destinct line of demarkation be- 

 tween the defoliated area and the unaffected portion of the 

 forest. The defoliated portion having the appearance of a for- 

 est in winter, while the other was in full leaf. In this respect, 

 the work of the caterpillars resembled one of the characteristic 

 features of the trouble caused by the destructive pine bark 

 beetle, which appeared to concentrate its forces on a few trees, 



