16 



beetles before they enter the bark and when they emerge, while the 

 larva destroys the larva and broods in the bark. 



A red-bug enemy of bark-beetles. A small, red to brown Heniipter- 

 ous bug of the family Acanthiidae and subfamily Anthocorina was 

 found in all stages of development, associated with colonies of the pine- 

 destroying beetle and its allies, in the bark of recently attacked living 

 and dying trees. These little relatives of the bedbug and the flower 

 bugs are recognized as aggressive enemies of bark beetles, both in the 

 East and West. The one found in the Black Hills is evidently Pizos- 

 tethus californicus Reut. The adult is about 3 mm. long, slender, 

 grayish, and exceedingly active. The young forms are usually bright 

 red, active little creatures which attack and suck out the liquids from 

 the bark beetles and their larvae. The adult bug also attacks and 

 kills the adult bark beetles. While this is a common and active enenry 

 of the smaller bark beetle, it probably does not render much service 

 toward checking the ravages of the destructive species. 



Other predaceous beetles. There are also a number of predaceous 

 beetles of the families Colydiidae, Tenebrionidae, Histeridae, and 

 Staphylinidae which were found in greater or less numbers in the 

 bark of infested trees, but their exact relation to the destructive 

 beetle was not determined. 



PARASITIC INSECTS. 



Several parasites belonging to the order Hymenoptera and families 

 Braconidae, Chalcididae, and Proctotrupidae were found to be enemies of 

 the smaller bark beetle larvae and adults, but none were found attack- 

 ing the pine-destroying species. Therefore there does not seem to be 

 much service rendered by this class of insects, which are usually so 

 efficient in reducing the numbers of bark beetles. 



PARASITIC FUNGI. 



A few examples of the adults and larvae of the pine-destrojdng beetle 

 were found which had evidently been killed by a fungus disease, but 

 this was by no means common enough to have rendered any service 

 in checking its ravages. 



BIRDS AS ENEMIES OF THE DESTRUCTIVE BEETLE. 



A few old dead trees and some which had been recently infested 

 which showed evidence of the beneficial work of woodpeckers were 

 observed in some localities, but hundreds of other insect-killed trees 

 showed no trace of work by the birds. Therefore there appears to be 

 very little service rendered from this source. This is evidently due 

 to a scarcity of the birds and to the fact that the habit of the insect 

 transforming to the adult in the inner bark makes it less accessible to 

 the birds than are the spruce-destroying beetle and other bark beetles 

 which undergo this change in the outer bark. 



