15 



INSECT ENEMIES OF THE FOLIAGE. 



tittle time was had to collect or study the enemies of the foliage, 

 it from general observations there was no perceptible injury from 

 this class of depredators. 



NATURAL ENEMIES OF THE DESTRUCTIVE AND INJURIOUS 



INSECTS. 



Numerous species of predaceous. and parasitic insects were found 

 associated with the primary and secondary enemies. Some evidence 

 was found of the beneficial work of birds, and a few examples of the 

 pine-destroying beetle were found that had been killed by a disease, 

 but in no case was there sufficient evidence to indicate that anj T of 

 these natural enemies, or all combined, were in sufficient numbers to 

 render any special service toward bringing the trouble to an end. 

 They were undoubtedly rendering some service, however, in prevent- 

 ing the rapid multiplication of the pine destroyer, which would other- 

 wise occur. 



PREDACEOUS ENEMIES. 



TJir 1)1 uish-green predaceous beetle (Trogosita virescens Fab.). This is 

 an elongate, flattened, shining, green beetle, varying in length from 

 10 mm. to 13 mm., and in width from 3 mm. to 4 mm. The larva 

 is a long, slender, reddish to whitish worm, with shining black head 

 and prothoracic plates. This recognized predatory enemy of bark- 

 infesting insects was frequently found associated with colonies of the 

 pine-destroying beetle and the secondary enemies, and a few adults 

 were found hiding beneath the flakes of outer bark. This widely dis- 

 tributed insect in North America has not been sufficiently studied to 

 determine its true relation to the destructive enemies of the trees, but 

 it is evidently quite beneficial. 



Clvi-'nl ~!>"'fk'$ and th<-<r larvce. The slender, reddish larvae of unde- 

 termined species of this class of predaceous enemies of bark beetles 

 were found in small numbers in the bark with the broods of the 

 destructive and other species of bark beetles. This class of beneficial 

 insects usually renders great service in reducing the numbers of the 

 destructive and injurious species. Therefore their scarcity in this 

 region may have had much to do with the rapid multiplication and 

 spread of the pine-destroying Dendroctonus. While collecting speci- 

 mens of bark beetles from saw logs in a mill } T ard at Boulder, Colo., 

 on August 25, one of these Clerids (dents nigrwentris'LfiG.) was very 

 common. The active, ant-like adults, which are black, marked with 

 transverse patches of gray, vary in length from 6 mm. to 8 mm., and in 

 width from 2.5 mm. to 3 mm. The larva is a slender, pale red worm. 

 The adult feeds on and destroys great numbers of the adult bark 



