42 CALIFORNIA AGRICULTURAL ExTENsiON Service [Ciro 42 
juices from the interior and, therefore, are not subject to control by 
poisons on the surface of the leaves, bark, or fruit. Instead some 
material must be applied directly to the insects and thus cause death 
by contact. Such materials are called contact insecticides. 
A few insects of the peach are not readily controlled by either 
contact or poison materials, but require special means of control 
Fig. 11.—TUsing paradichlorobenzene for control of peach borer. Left, the 
ring method, first step: leveling the surface of the ground for a space of two or 
three feet in diameter about the tree. Right, second step: the paradichlorobenzene 
applied in a ring two or three inches wide, the inside about three inches from the 
bark of the tree. (From California Agr. Exp. Sta. Bul. 411.) 
Pacific Peach Tree Borer, Aegeria opalescens Hy. Edw.—This 
insect is serious in certain counties and is distributed throughout 
coastal, eentral and southern parts of the state. The dark wasp-like 
moth lays its eggs in the early spring on the trunk of the tree a few 
inches above the ground. The larvae which hatch in fifteen to thirty 
days, burrow into the trunk and main roots, and may girdle the tree, 
thus killing it. Gum and frass indicate the presence of the borer. 
Control measures are simple since the discovery of the paradichloro- 
benzene treatment. This crystalline material is sprinkled in a circle 
around and near the base of the tree and covered with soil (fig. 11). 
The heavy vapor penetrates the soil and burrows, killing the insects. 
The material should be applied in the late summer and fall when the 
50il is warm and the moisture not excessive. 
Flat-headed Apple Tree Borer, Chrysobothris mali Horn.—The 
beetles lay their eggs, especially in sunburned or injured areas or on