43 



274. Tlie Four-Winged Parasites (Order Hymenoptera. Families Ichneumonidse, 

 Braconidx, Chalddidse, etc. ). 



Exhibit: Two larval galleries of the rigid cypress borer ((Erne rigida) , in one of 

 which the insect attained full development, while in the other it was attacked and 

 killed by a parasite, Bracon sp. 



Adults and cocoons of several species which attack larvae of butterflies and moths. 



Adults and cocoons of several species which attack larvae of wood-boring insects. 



THE TROGOSITIDS. FAMILY TROGOSITID^E. 



275. The Green Trog-ositid (Trogosita virescens Fab.). 



A very important enemy of nearly all the larger and more destructive bark-beetles. 

 The adults conceal themselves in the outer bark, and the larvae enter the galleries 

 and prey upon the insects therein. 



Exhibit: Adults. 



THE COLYDIIDS. FAMILY COLYDIIDiE. 



276. The Tuberculate Colydiid {Aulonium tuberculatum Lee). 



The adults enter the galleries and with the larvae feed upon various species of bark- 

 beetles in all their stages. 

 Exhibit: Adults. 



277. The Line-Marked Colydiid (Colydium lineola Say). 



The adults enter the galleries and their larvae feed upon the developing brood of 

 various species of Ambrosia beetles. 

 Exhibit: Adults. 



SECTION III. 



SPECIAL INVESTIGATIONS. 



[In connection with the exhibit of the Bureau of Forestry.] 



DESTRUCTION OF PINE BY BARK-BEETLES IN THE BLACK HILLS 

 FOREST RESERVE, SOUTH DAKOTA. 



CASE 49. 



278. The Pine-Destroying Beetle of the Black Hills (Dendroctonus ponder- 



osse Hopk. ). 



Attacks healthy pine and spruce in the Black Hills of South Dakota, and Kocky 

 Mountain region. The adult beetles excavate characteristic galleries in the inner 

 bark of dead, dying, and healthy trees. Their eggs are deposited along the sides 

 of these galleries, and the larvae developing from them mine the inner bark. Very 

 destructive. 



Exhibit: Adults, larvae, pupae, pitch tube on bark of living tree at entrance to 

 gallery of adult beetle; completed galleries of adults and mines of young larvae in 

 bark of living pine, showing characteristic appearance of bark in August of the year 

 of attack; surface of wood grooved by galleries of the adult, showing characteristic 

 appearance in August of the year of attack; gallery of adult, larval mines, and 

 pupal chambers in inner bark, showing characteristic appearance in June of the 

 year following attack; appearance of inner bark in August of the year following 

 attack, after the emergence of the brood; scoring chip from railroad cross-tie from 

 tree killed by beetles, showing characteristic markings on surface of wood. 



