1988] Cornell, Stamp, & Bowers — Hemileuca lucina 47 
Each larva was individually marked using a three-dot, color- 
coding system with seven colors of acrylic paint (Liquitex™) and 
weighed 4 days after each molt. Reliable identification of individu- 
als was maintained by isolating individuals just before molt, remark- 
ing them after molt and then returning them to their groups, within 
12 hr of separation from the group. Thus, larvae could be identified 
individually throughout their development and during testing, while 
remaining with their sibling groups. In contrast, other studies have 
isolated individuals for substantial periods (Greenblatt and Witter, 
1976; Edgerly and Fitzgerald, 1982), which may alter larval 
behavior. 
During the first through fifth instars, larvae from each group were 
tested for distance traveled as an index of activity. We did not test 
the last (sixth) instar because those larvae are not gregarious. Lar- 
vae were tested at 4 days after molting and were starved for 24 h 
prior to testing. The test arena was a petri dish (diameter 14 cm) 
lined with a sheet of paper on which were drawn a series of concen- 
tric circles, 2.5 mm apart. A paper rope was suspended vertically by a 
string so that the bottom touched the center of the dish. The ropes 
were made from paper towels soaked in 50% ethanol and twisted 
into 300-rnm lengths. When dry, the ropes were marked in pencil at 
2.5 mm intervals. These ropes simulated the natural form of a 
branch along which larvae forage. A clean rope was used for each 
test. A sprig of S. latifolia was placed at the top of the string and a 
heat lamp was placed 1 m above that to induce the larvae to travel 
up the rope. 
At the beginning of the test, the larvae were arranged on the paper 
sheet in a ring around the base of the rope. Larvae faced towards the 
rope and were 5 cm from it. They then were allowed to move around 
the dish or up the rope for 8 min for the first through third instars 
and for 4 min for the fourth and fifth instars. The reduction in test 
time was necessary due to an increase in overall larval activity in the 
later instars. The rank order of all larvae on the rope and the dis- 
tance each had traveled from the starting point were recorded at the 
midpoint and end of each trial. 
Each group of larvae was tested in 5 trials during each instar. 
Because individual larvae could be identified throughout the tests, 
we were able to obtain data on behavior of individuals at several 
levels: 1) variation within a trial (i.e. did larvae change ranks during 
