410 WEST VIRGINIA EXPERIMENT STATION. 



Hypophloeus cavus Lee. Frequently met with in the brood 

 galleries of D. frontalis \ but no observations were made as to 

 the habits of the adult and larva. 



Hypophloeus parallelus Welsh. Found in pine bark with 

 D frontalis, and is a common species in the galleries of 8col>- 

 tids in bark of coniferous and deciduous trees. It is recognized 

 as an enemy of bark beetles. 



ROBBERS. 



Under this head D. frontalis has a few enemies, especially 

 in the large, bark-boring grubs, the larvae of Monohammus 

 species, and Rhayium lineatum Fig. LXXXV. The latter cuts 

 a wide swath through the inner bark, which, if infested with 

 Scolytids must be destroyed in great numbers both by being 

 robbed of their food supply, and killed outright by the grubs in 

 their operation of excavating their mines. 



BIRDS. 



Mumerous trees were observed during the investigation which 

 had the outer flaky bark removed by the birds from the entire 

 trunk ; giving the bark of such trees a conspicuous, reddish ap- 

 pearance by which they could be easily detected from a con- 

 siderable distance. Upon examination, it was found that the 

 birds had removed the outer layer of dry bark in order to se- 

 cure the larvae, pupae, and young adults of D. frontalis from 

 the pupa cases, which as has been shown, Fig. LX1X, often 

 occur in great numbers quite near the surface. It was a no- 

 table fact however, that while one tree would be completely 

 stripped of its outer layers of bark, hundreds of other trees in 

 the same section of the forest, or in the same group of infested 

 tr>es, showed no indication of the work ot birds. It appears 

 that if a woodpecker commences on ;i tree in the bark of which 

 thsre is an abundant supply of insects, it confines its attention 

 to that tree alone, and that all the other woodpeckers in the 

 same locality are attracted <o it until the supply is exhausted, 

 when they turn their attention to another tree. So that while 

 a great number of insects are destroyed, it contributes very lit- 

 tle towards checking the invasion. In fact, large numbers of 



