THE PINR INVESTIGATION. 379 



SOME OF THE PRINCIPAL INSECTS ASSOCIATED WITH THE 



PINE TROUBLE. 



The Scolytids. 



Order COLEOPETRA, Family SCOLYTIDAE. 



The insect which was primarily to blame for the devastations 

 in the pine and spruce forests in 1890 to 1892, as well as a num- 

 ber of its principal allies in attacking and killing the trees and 

 the subsequent destruction of the wood belongs to the family 

 of beetles known as Scolytidae: a family which is of special 

 importance and interest on account of the destructive habits of 

 a number of its representatives; especially in I heir relation 

 to forest, shade, and fruit trees. 



SOME GENERAL FEATURES AND HABITS OF THE FAMILY. 



All of the individuals belonging 10 the family Scolytidae 

 have the same general appearance as those illustrated and de- 

 scribed on the following pages. Of the 160 or more species that 

 are known to occur in America, north of Mexico, Dendroctonus 

 terebrans, Fig. LXXlll, is the largest and Crypturgus pusillus 

 is among the smallest examples. 



GENERAL HABITS. 



They infest, as a rule, the bark and wood of trees and shrubs; 

 but some of the species attack the roots and stems of herbaceous 

 plants, while a few are found in seeds and dried vegetable mat- 

 ter. 



THEIR PREFERENCE FOR CONIFEROUS TREKS. 



A large number of species prefer to attack and breed in con 

 iferous trees; but almost all kinds of trees and shrubs are in- 

 fested by one or more species, and some species infest a great 

 variety of trees. The oaks, hickories, tulip, beech, ash, elm, 

 maple, red-bud, and sumach are attacked, as are the different 

 kinds of fruit trees; but the pines are their special favorites, 

 since more than one-fourth of the entire known species in this 



