(E)-5, (Z)-7-DODECADIENAL, A SEX PHEROMONE COMPONENT OF THE WESTERN TENT CATERPILLAR, MALACOSOMA CALIFORNICUM (LEPIDOPTERA: LASIOCAMPIDAE)

Tent caterpillars of the genus Malacosoma frequently appear in outbreak numbers causing widespread defoliation of trees and shrubs in North America. The western tent caterpillar, M. californicum (Packard), with six subspecies, occurs over most of temperate western North America and although there is a large number of host plants on which it will oviposit and feed (Stehr and Cook 1968), most have little commercial value. We report here the identification of a component of the female sex pheromone of M. californicum.

BEHAVIORAL STUDIES ON MALACOSOMA DISSTRIA (LEPIDOPTERA: LASIOCAMPIDAE)

First-stage forest tent caterpillar larvae were tested for the presence of active and sluggish behavior types such as Wellington found in Malacosoma californicum pluviale (Dyar). Larvae capable of directed movement towards a 30 w light source were classified as active. Larvae were tested on 3 consecutive days, and only a small percentage responded on all 3 days. A much larger percentage remained sluggish throughout the period. Chi-square tests confirmed that the differences in response were not random. There was a tendency for some larvae to respond to light during the test and for others not to respond. The reduced consistency in the response of "active" larvae in M. disstria Hübner compared with that reported for M.c. pluviale may be partly due to real behavioral differences, but it also may be partly due to some procedural differences between our tests and Wellington’s.

EFFECTS OF THE PLANT GROWTH REGULATOR INDOLEBUTYRIC ACID ON THE GROWTH, DEVELOPMENT, AND REPRODUCTION OF THE WESTERN TENT CATERPILLAR, MALACOSOMA CALIFORNICUM PLUVIALE (LEPIDOPTERA: LASIOCAMPIDAE)

The synthetic plant growth regulator indolebutyric acid delayed pupation, produced lighter pupae, and interfered with the larva-to-pupa molt of the western tent caterpillar, Malacosoma californicum pluviale (Dyar), when it was mixed with water (0.1 g/1.) in which cut foliage for rearing the larvae was kept. Treatment of very young larvae led to adults that produced more and better eggs than the controls. Treating older larvae produced antigonadotrophic effects.

The influence of behavioral differences among tent-caterpillar larvae on predation by a pentatomid bug

Active larvae of the western tent caterpillar, Malacosoma californicum pluviale (Dyar), were stalked more consistently by the predator, Podisus maculiventris Say, than their sluggish counterparts. In the fourth instar, the active individuals were too small to defend themselves, so they were eaten more frequently than sluggish larvae. In the fifth instar, active larvae defended themselves more successfully, whereas sluggish larvae did not. Among these older larvae, therefore, fewer active and more sluggish individuals were successfully attacked.