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 and flat-head apple-tree borers. 
THE ROUND-HEADED APPLE-TREE 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 frass or "sawdust" to drop out, and often there 
a b c d 
Fig. 36.— Saperda Candida: 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 ground. 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 
