Colonies of the Eastern Tent Caterpillar Malacosoma americanum (Lepidoptera:Lasiocampidae) Abandon Trails to Depleted Feeding Sites and Follow the Most Direct and Shortest Pathways Between their Tent and Food-Finds

Laboratory studies were conducted to determine the ability of colonies of the eastern tent caterpillar, Malacosoma Americanum (Lepidoptera:Lasiocampidae), to abandon long-lived pheromone trails to depleted feeding sites and to follow the most direct and shortest of pathways between their tent and new food-finds. For the first of these studies, the caterpillars in all but one of fourteen colonies quickly abandoned well established trails to sites depleted of leaves after discovering and feeding at unexploited patches elsewhere. Interval-sampling of video frames of caterpillars moving over three-choice mazes between their tent and feeding sites in the second study showed that the caterpillars strongly favored trials that directly connected their tents and feeding sites, largely abandoning spur trails laid down during the exploratory phase of the contemporary foray. In the third study, all of the caterpillars in sixteen of seventeen colonies selected the shorter of two pathways between their tent and a feeding site on their first return trip to the new food-find or after one or more additional forays. Together, these studies indicate that the caterpillar’s bi-level, trail-based foraging system enables colonies to efficiently navigate the expansive three-dimensional complex of long-persistent trails that lie between their communal tent and distant food-finds.