Forest Protection 181 



enlarge their webs from time to time to include more 

 food. When a month old, they descend trees to pupate 

 on or in the ground. 



To destroy these insects, burn the web carefully, and see 

 that none escape. Spray with arsenical poisons about 

 the time the caterpillars appear. Hogs turned into a 

 plantation will root up and eat thousands of the cocoons. 



The locust borer 



This insect (Cyllene robinice) has done an enormous 

 amount of damage not only by destroying trees, but also 

 in many parts of the country by forcing the abandonment 

 of an attempt to plant the black locust, which would 

 otherwise be a very valuable plantation tree. 



The beetle is J to f inch long, brightly marked with 

 golden yellow, with the antennae and legs dull yellowish. 

 The pupa is f inch long, flattened and yellowish. The 

 larva is -$ to y 7 ^ inch long, flattened and club-shaped. 



Beetles appear on the trees in great numbers in Septem- 

 ber. The eggs are laid in crevices of the bark. They 

 soon hatch and the larvae immediately bore into the cam- 

 bium, where they spend the winter. With the warm 

 spring days, they start activities again, only this time they 

 bore into the heartwood. The gallery is about a quarter 

 of an inch in diameter and usually curves upward. The 

 larvae pupate about the middle of July and the beetles 

 come out in September. 



The presence of the insects is evidenced by holes in the 

 bark from which the sap runs, a deadening of the cam- 

 bium and consequent loosening of the bark, and sawdust 

 around the base of the tree. As a rule, they do not attack 



