12 BULLETIN 50, HAWAII EXPERIMENT STATION. 
INSECTS INJURING THE FOLIAGE. 
Japanese Beetle (Adoretus tenuimaculatus). 
The Japanese beetle perforates the foliage of the sweet-potato 
plant. The pest can be brought under control by spraying the under 
side of the foliage with a mixture containing 1 pound of lead arsenate 
in 20 gallons of water. 
Sweet-Potato Leaf-Miner (Bedellia orckilella). 
The leaf-miner, after the stem borer, is perhaps the most destructive 
insect enemy of the sweet-potato vine. Its injuries are confined to 
the foliage, which as a result presents a notched and withered appear- 
ance and bears traces of excrement. The newly hatched , larvae 
penetrate the leaves and feed upon the green coloring matter. The 
leaves gradually lose their color and wither, and the leafstalks drop. 
The leaf-miner can best be controlled by the removal and burning 
of severely infested foliage and by the practice of clean cultivation. 
Sweet-Potato Sphinx (Rerse convolvuli). 
During the rainy season the sphinx caterpillar periodically appears 
on sweet-potato vines. The eggs are usually laid on the under side 
of the leaves of the wild morning-glory Ipomcea digitata, and occasion- 
ally on those of the sweet potato. The caterpillar is from 2 to 6 inches 
long, ranges from light green to dark brown in color, and is charac- 
terized by a single black horn. 
As a means of control, all host plants, such as morning-glory and 
pigweed {Portulaca oleracea), should be destroyed. On vacant lots 
in the Waialae district of Oahu wild morning-glory vines should be 
destroyed to protect the surrounding fields of sweet potatoes from 
attack by the sphinx caterpillar. 
Spraying the under side of the leaves with arsenate of lead solution 
(1 pound of the arsenate to 20 gallons of water) will materially reduce 
the number of caterpillars. This pest may also be kept in check by 
picking the larvae from the vines growing on small areas. 
Sweet-Potato Leaf-Roller (Phlyctxnia despecta). 
This leaf-roller is one of the minor insect pests attacking the foliage 
of the sweet-potato crop. In extreme cases it skeletonizes the leaves 
and envelopes the remaining structure in a filmy web. The young 
caterpillar, although colorless, usually appears green, owing to the 
green contents of the alimentary tract, which can be seen through 
the body. Its hiding place is on the under side of the leaves. 
An application of lead arsenate to the leaves is recommended as a 
control measure. Clean cultivation should also be practiced. 
INSECTS INJURING THE STEM. 
Cutworm (Agrotis ypsilon). 
Cutworms attack the sweet-potato vine at night during the early 
growing period, eating the terminal and axillary buds and sometimes 
completely cutting oil the growing vine at the base. 
As a control measure the use of poison bait, composed of 1 pound 
of molasses, J pound of lead arsenate, and 10 pounds of bran, 
thoroughly mixed and spread near the base of the vines, is recom- 
