302 INSECTS AFFECTING VEGETATION 



after the leaves of the locust are well grown. Eggs are deposited 

 upon the surface of the leaves, and the young larva makes its way 

 out through the under side of the eggshell into the tissue of the leaf, 

 feeding until grown and pupating between the two layers of epider- 

 mis. The adults feed upon the leaves and may be found in the 

 groves throughout the summer. The most satisfactory method of 

 combating the pest is spraying thoroughly with arsenicals as soon 

 as the locust leaves are out, that the beetles may be killed before 

 egg laying is accomplished. This of course is impracticable for for- 

 est plantings. 



The Locust Borer. So destructive is the work of this insect 

 upon locust trees that in some places the growing of a perfect tree is 

 an impossibility. The adult belongs to that class of insects known 

 as the long-horned borers. It is a black beetle, brilliantly marked 

 with yellow lines; the long antennae and the legs are dull yellow 

 and the length varies from 1% to 1% inches. At the time the golden 

 rod blossoms the adults appear and egg-laying commences. The fe- 

 male hurries about over the trunk of the tree, and when a crevice 

 is found which suits her fancy she deposits a single white egg, then 

 continues her search for another place. 



The newly hatched larva bores through the outer layer of bark 

 and rests in the white layer next the wood through the winter. With 

 the advent of spring feeding is resumed, and the larva eats its way 

 well into the body of the tree. If the tree is small the trunk may be 

 almost severed and a slight wind may blow it over. The full grown 

 larva is a creamy, club-shaped, footless grub, about % inch in 

 length. 



The pupal stage is passed within the burrow, the adult emerg- 

 ing at the time previously stated. There remains to be found a 

 practicable, effective, combative measure for this pest. Spraying the 

 trunks of the trees with a repellant just previous to the time the 

 females deposit their eggs is of some value, though not wholly effec- 

 tive. Whale oil soap and white-wash were applied to adjoining 

 rows of trees in the Station planting, resulting in a slightly lessened 

 injury during the season following. Injecting carbon bisulphide 

 into the tunnels, by the use of an engineer's oil can, previous to the 

 appearance of the adults and closing the tunnels with grafting wax 

 was also partially successful in controlling the pest. 



The Locust Twig Borer. The presence of this insect in yellow 

 locust groves is quite easily detected by its work upon the twigs of 

 the tree. The smaller twigs become swollen and after a time white, 

 sawdust-like material commences to drop from an opening in the en- 

 larged section. The injury is the work of a lepidopterous larva, 

 which upon the completion of growth, drops to the ground and 

 pupates among the dried leaves. In this position the winter is 

 passed. Although not exceptionally injurious it harms the tree to 

 a certain extent. It is a question, however, whether combative meas- 

 ures are worth while. Should action be considered necessary, the 

 Affected twigs may be cut and burned while the Iarva3 are still pres- 



