VARIATION AND DEVELOPMENTAL CHANGE IN 
ACTIVITY OF GREGARIOUS CATERPILLARS, 
HEMILEUCA LUCINA (SATURNIIDAE) 
By Jennifer C. Cornell 1 , Nancy E. Stamp 2 , 
and M. Deane Bowers 1 
Introduction 
Variation in behavior of individuals within an aggregation may 
result in a nominal division of labor or roles (Wilson, 1971). Indi- 
viduals may play a particular role throughout the course of devel- 
opment or change roles often. Such variation seems to occur in tent 
caterpillars of the genus Malacosoma (Lasiocampidae) ( M . califor- 
nicum pluviale, Wellington, 1957; M. disstria, Laux, 1962 (as M. 
neustria ), Greenblatt and Witter, 1976; M. americanum, Edgerly 
and Fitzgerald, 1982). Evidence for permanent polyethism (in terms 
of active or inactive individuals) was reported for M. c. pluviale by 
Wellington (1957) but was not found by Myers (1978), and Welling- 
ton’s statistical analysis has been criticized (Papaj and Rausher, 
1983). In other tent caterpillar species, individuals were not consist- 
ently active or inactive but shifted from one to the other state over a 
few days (Laux 1962; Greenblatt and Witter, 1976; Edgerly and 
Fitzgerald, 1982). Nonetheless, those larvae that were currently 
active played a critical role in determining the foraging pattern of 
the aggregation. For instance, small subgroups of M. americanum 
larvae left the tent before the main body of caterpillars, fed, and 
returned, depositing a fresh recruitment trail that the other larvae 
then followed to the feeding site (Fitzgerald, 1980). 
To date, only Malacosoma species have been investigated for 
behavioral variation among larvae in aggregations even though 
many gregarious species exhibit distinct foraging patterns where 
individuals of various activity levels might be important. Further- 
more, none of the Malacosoma studies assessed activity instar by 
'Museum of Comparative Zoology, Harvard University, Cambridge, MA 02138, 
USA 
department of Biological Sciences, State University of New York, Binghamton, NY 
13901, USA 
Manuscript received by the editor February 24, 1988. 
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