Effect of Monocrotophos on the Leaf Eating Caterpillar, <i>Opisina arenosella</i> Walk, when Injected into the Trunk of the Coconut Palm

Monocrotophos injected into the trunk of tall coconut palms (15 to 20 m) at 3.0 and 6.0g a.i. per palm, was translocated and accumulated in the leaves in quantities sufficient to kill the leaf eating caterpillar, Opisina arenosella. Monocrotophos was injected, as an undiluted 60'/ WSC, into freshly made holes, 15cm deep and 2cm in diameter, made at a point lm above the ground. Only one hole per palm was used for this treatment. Bioassays in the laboratory and assessments of the natural population of caterpillars on the experimental palms indicated that the insecticidal effect persisted in the leaves for about four to six months. This treatment would therefore be adequate to control a succession of larvae hatching out of eggs laid over a period of time.