INSECTS 



173 



discolored, undermined bark. Generally this borer does not show 

 a preference for trees of vigorous, unimpaired growth, but attacks 

 weakened, devitalized trees ; when these are lacking, however, it 

 attacks sound trees. 



Remedies. The control measures for the flat-headed borer and 

 the round-headed species are the same. The trunks of trees are 

 sometimes painted with deterrent compounds, such as whale-oil 

 soap, carbolated soft soap, etc., to discourage egg laying. These 

 remedies should be applied early in the spring as thick pastes, and 

 renewed at intervals through- 

 out the summer. 



Round-headed borer (Saperda 

 Candida, Fab.). The adult of 

 this species is a large beetle, 

 nearly one inch in length, 

 yellowish-brown above and 

 silvery-white beneath. Two 

 broad, white, slightly-curved 

 stripes traverse the entire 

 length of the back. The larva 

 is a large, footless, light- 

 yellowish grub, about one inch 

 long when fully grown, taper- 

 ing in a graduated scale from 

 segment to segment through- 

 out its entire length. The head is darker than the body and 

 slightly larger in diameter. The pupa is slightly shorter than the 

 larva and looks something like the adult. 



The beetles appear in May and June, and eggs are laid soon 

 after. The eggs are deposited by the females in slits cut in the 

 bark near the base of the tree, and are hatched in two or three 

 weeks. The larva at once tunnels into the bark and feeds on the 

 sapwood during the first year, cutting a disk-shaped burrow, at 

 the bottom of which it passes the winter, not feeding again until 

 the spring of the second year. The burrow is enlarged greatly the 

 second year by the renewed feeding of the larva, and the castings 

 are pushed out through holes cut in the bark. In small trees 

 the trunk is often completely girdled by these holes. The larva 



Fig. 78. Round-headed apple-tree borer 

 (natural-size dorsal, ventral, and lateral 

 views). (Photograph by W. E. Rumsey) 



