39 



sometimes done by both the grub and the beetle. The grubs, to reach 

 the adult condition, pass through a complete change or metamorphosis, 

 like caterpillars, but do not spin a silken cocoon. The grubs do not 

 have the prolegs that are found in caterpillars. The forms to be 

 noticed below may be arranged as follows: 



1. Boring in the twigs Apple twig-borer. 



Boring in the trunk or larger branches 2 



2. Making tiny circular holes in the bark '.'.'.".".".'.".■.".".".' Fruit-tree bark-beetle! 



Making a sinuate crack or depression Sinuate pear borer. 



Piscolored spots on the bark Round-head an<l flat-head apple-tree borers. 



THK ROUND-HKADED APPLE-TKKE BORER. 

 (Saperda Candida Fab. — fig. 36.) 

 Discolored places on the bark near the base of the trunk may indi- 

 cate the presence of this borer. Sometimes the bark cracks over the 

 burrow and allows the f rass or ' ' sawdust " to drop out, and often there 



Fig. 36. 



a b 



-Saperda Candida: 



c d 



a, b, larva; c, beetle: d, pupa, enlarged. (Chittenden.) 



is some exudation of sap. Every unnatural-looking spot near the base 

 of the tree should be examined. The adult of this borer is a grayish, 

 long-horned beetle with two white stripes along its back. They appear 

 in June and July, and lay their eggs in little slits in the bark made by 

 the beetle near the base of the trunk. The larvae or grubs soon hatch 

 and bore beneath the bark, feeding on the sapwood and inner bark, 

 and making flat, shallow cavities, partially filled with frass. The 

 grubs are nearly cylindrical, pale yellowish in color, and when full- 

 grown about an inch long. On the approach of winter they work 

 downward, often below the surface of the gi-ound. In .spring they 

 begin to feed again, boring upward. In this manner they feed all 

 summer until cold weather, when they again hibernate. In the spring 

 they resume work, but now they bore more irregularly and further 

 into the tree. In early fall they bore close to the surface, work back 



