52 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 



festation may occur from a large number of sources outside the 

 orchards. 



The control of this insect is seldom attempted, for the actual loss 

 does not, in most cases, justify the cost of treatment. Where control 

 is desirable the oil emulsion and miscible oil sprays as recommended 

 for the black scale should be used. 



Natural enemies have never been considered of any consequence 

 in the control of this scale, although there are both ladybird beetles 

 and hymenopterous parasites that prey upon it in California as else- 

 where. 



THE BEANCH AND TWIG BOEEE 



Polycaon confertus Leconte 



Figure 7 



The work of this beetle, which consists of small, round holes from 

 one-eighth to one-fourth of an inch in diameter and usually less than 

 an inch in length at the base of a bud or in the fork of a small branch, 

 is familiar to many orchardists. Occasionally one also finds the 

 beetle itself at work in the holes. It is small, brown and black and 

 about half an inch long. The object of its work is probably to 

 secure food, as no eggs are deposited or young reared in anything but 

 dead wood, while the burrows in orchard trees are always made in 

 perfectly healthy and living tissue. The injury is due to the breaking 

 of the twigs at the holes, and the improper pruning of the trees which 

 results. The young trees suffer most, though old trees are quite as 

 commonly attacked. Plants known to be thus injured are: almond, 

 apple, apricot, cherry, currant, fig, grape, lemon, olive, orange, peach, 

 pear, plum and prune. As previously stated the insect normally 

 breeds in dead wood, chiefly of the madrone, oak, and old grape canes 

 where the larvae may often be found in great numbers. 



The beetle occurs generally throughou the state, but has been most 

 annoying in the Sacramento, San Joaquin, and Santa Clara Valleys 

 and the central coast region. The attacks are spasmodic and of short 

 duration and the damage done through a succession of years is really 

 slight. Eegular control measures have never been tested out because 

 they are generally unnecessary. The elimination of the dead wood 

 in which the insect breeds might be suggested as a preventive meas- 

 ure and in young orchards, where the attacks are severe, it might be 

 advisable to go over the trees about once a week and kill the beetles 

 in the burrows with a wire or knife blade. 



