THE COLEOPTERA 



131 



borers because the thoracic segments are circular in outline and the 

 tunnels they produce are therefore also of this shape. The larvae them- 

 selves are soft, whitish or yellowish grubs, with strong jaws, and most of 

 them have no legs. The eggs are usually laid on the bark of the tree and 

 the larvae live on the wood they tunnel out, for a varying period, usually 

 2 or 3 years, and pupate in the tunnels just beneath the bark, 

 through which the emerging beetle finally gnaws its way and escapes. 



FIG. 123. Cerambycid (Monohammus), natural size, showing long antennae. (Original.) 



Some species cut the stem in which they live, nearly through, and when 

 it breaks off, fall with it to the ground, thus pruning the tree. Those 

 which tunnel in the heart-wood of timber trees often greatly reduce the 

 value of the timber by their holes. Some species attack sound wood and 

 apparently vigorous trees, while others seem to prefer trees already un- 

 healthy, for their food. The family is a large one and contains many 

 forms injurious to shade and forest trees. 



The Round-headed Apple-tree Borer (Saperda Candida Fab.). This 

 serious enemy of the apple tree is found practically everywhere in the 

 eastern United States except in the extreme South, and westward into 

 Minnesota, Iowa, New Mexico and Texas. It also attacks the service 

 tree, pear, quince, thorns, mountain ash, and a few other Rosaceae. The 

 adult beetle (Fig. 124) is a little less than an inch long, pale brown above, 

 with a pair of white stripes extending backward from the head across 

 the pronotum and along the elytra to their tips at the hinder end of the 

 body. Beneath, it is silvery white. It appears during the late spring 

 and summer months and lays its eggs singly here and there in small slits 

 it cuts in the bark near the base of the tree, laying about 15 to 30 in all. 

 On hatching, 2 to 3 weeks later, the larva burrows through the bark to 

 the sap-wood, and there makes broad, rather shallow galleries just under 

 the bark and in general working downward. The bark over these gal- 

 leries frequently dries and cracks, or the borer makes holes in it, letting 



