222 BARK-BEETLES; ENGRAVER-BEETLES. 



in all directions, making fanciful carvings and engravings on the 

 inner side of the bark and the surface of the wood, hence the 

 name "engravers." 



Many species have a habit similar to the one quoted by Prof. 

 Comstock from Dr. Lindemann, who writes : "that in the case of 

 Tomicus typographies the original tunnel is begun by the male, 

 who makes a little chamber in the bark ; afterwards the female 

 comes to him in this chamber, and later she continues the mine 

 begun by her mate, making the long central tunnel from which 

 the tunnels of her off-spring extend. Thus we see that all the 

 members of a single family have a share in making one of these 

 engravings." 



Whenever a tree has been invaded by a number of such in- 

 sects the trees are killed, and in other cases the timber is greatly 

 injured by the burrows in the solid Avood. It seems as if these 

 beetles preferred sick or dying trees, in which case they act sim- 

 ply as scavengers, removing the dead material to make room for 

 new growth. Beside forest trees, fruit-trees are also attacked by 

 some members of this large family, and in some very few cases 

 even the roots of the clover suffer. 



Those interested in such beetles should not fail to read the 

 important work of Dr. A. S. Packard, published by the U. S. De- 

 partment of Agriculture, entitled : "Insects Injurious to Forest 

 and Shade Trees," or the most interesting paper on "Ambrosia 

 Beetles" by H. (i. Hubbard in a recent bulletin (No. 7) of the 

 Division of Entomology, Washington, D. C, and the valuable 

 bulletin (No. 56) of the West Virginia Experiment Station by 

 A. D. Hopkins. 



THE APPLE BARK-BEETLE. 



( Monarthrum mali Fitch). 



In the genus Monarthrum the sexes are alike, and the males 

 assist the females in forming new colonies. Mr. Hubbard writes : 

 "The young are raised in separate pits or cradles, which they 

 never leave until they reach the adult stage. The galleries, con- 



