Insects of Shade Trees and Their Control. 483 
the course of their growth. When nearly full grown they are great 
travelers, especially from defoliated trees. When full grown the 
caterpillars spin delicate grayish cocoons of silk, mixed with hairs 
from their bodies, and within these cocoons they transform to pup 
(fig. 24, 6, c) and, about two weeks later, these change into moths 
(fig. 24, d, e, f) of which the females are wingless. Mating and egg 
laying take place soon afterwards. Three generations of the insect 
are produced annually in Washington, D. C.; two or only one north 
of that city. 
Remedies.—Destroy the eggs in the winter either by hand picking 
or scraping them off and burning, or by spraying or dabbing with 
creosote oil, mixed with turpentine to keep it“liquid in winter. As 
soon as injury by the caterpillars is noticed, spray infested foliage 
with lead arsenate (p. 11). Hand picking or any simple device will 
do for treatment of the eggs. For spraying purposes a spray pump 
is necessary, and the size of the equipment will vary with the amount 
of work to be done. A barrel pump mounted on a horse-drawn cart 
with one or two 50 to 100 foot leads of garden hose and a 10-foot 
bamboo rod with a spray nozzle at the end will do for a small town. 
Cities will find advantage in horse or motor-drawn power spray 
pumps. The catalogues of reliable spray-pump manufacturers, giving 
detailed information, are procurable in most seed, pump, or hardware 
stores and should be consulted. 
Essentials of successful control—Thoroughness, concerted com- 
munity action, and cooperation are essential for success. Leave as 
few surviving eggs or caterpillars as possible. Treatment of a tree 
here and there, now and then, protects no trees, not even those treated. 
All or most trees must be treated the same season, whether this be 
done by citizens individually or as a community organization. The 
trees attacked are usually large. Where spraying must be resorted 
to, the requisite apparatus is too expensive for the average individual, 
and can be bought (or hired) and operated only cooperatively, either 
through local governments or other civic organizations. 
LOCUST LEAF-MINER.” 
Evidence of work and seriousness——About the time the locust 
leaves become full grown they are often observed to turn brown, as 
if fire scorched. Entire trees and groves of locust may assume this 
appearance. But aside from marring their appearance the injury 
to the trees is generally less real than apparent. No later than the 
following spring the trees are sure to put out a fresh, healthy set of 
leaves, as if nothing had happened. 
*” Chalepis dorsalis Thunb. 
