I have recently done a fair amount of online research about gypsy moth caterpillars and sources I looked at say that older caterpillars feed on the trees primarily during the night and drop down and hide in dark sheltered areas during the day.
I work for someone who had a severe gypsy moth infestation last year and we tied burlap around several isolated trees to see if we could reduce the damage. At the height of the infestation we noticed that there were, at any given time during the day, 20-40 caterpillars circling the base of the burlap and sometimes successfully crawling over it. It looked like they were actively trying to climb up into the trees during the day, which seems to contradict everything I've read.
Can anyone offer any insight into this behavior?