35 
on the under surface of loosened bark a few inches from the root of 
a badly infested plum-tree. 
The removal and destruction of infested branches at the proper 
time of the year, that is, during the winter and spring, is the only 
measure practicable for the control of this pest. 
The winged insect has a blue-black head, thorax, and abdomen, 
the thorax with a narrow pale line each side, and the abdomen with 
a narrow^ pale yellow ring on the second and fourth segments, en- 
circling the body completely on the latter. The fore wings are 
transparent, with very narrow blue-black margins, and a narrow, 
straight, discal mark. The inner margin is sometimes scaled with 
pale yellow. The hind wings are transparent, with a very narrow 
outer margin and no discal mark. The spread of the wings is from 
15 — 26 mm., the smaller specimens being males. 
The Maple Borer 
(Sesia accnii Clem.) 
The worst of the borers of the maples, both hard and soft, very 
common and destructive to soft maples in Chicago, and common 
also in towns thruout the state, is a white or nearly white caterpillar 
(Fig. 37, a) about half an inch long when full grown, with a yel- 
low head and a neck shield of a paler tint. It is especially injurious 
to young trees, but usually originates in some surface injury which 
attracts the parent moth in search of a place of deposit for her eggs. 
Fig. 37. Maple Borer, Sesiu acerni: a, a, 
larvae; b, b, b, cocoons; c, adult; d, pupal 
skin left in mouth of burrow. 
