Social caterpillars

The collective behaviors of social caterpillars falls into five general categories: collective and cooperative foraging, group defense against predators and parasitoids, shelter building, thermoregulation and substrate silking to enhance steadfastness.

The most behaviorally sophisticated of the insect societies are found among the ants, termites, bees, and wasps. While these insects are technically classified as eusocial insects they are commonly referred to simply as the social insects. In this scheme of classification, other non-eusocial, gregarious species of insects are referred to as presocial, subsocial, quasisocial, or in some other manner that has the unfortunate consequence of suggesting that are not quite social. Yet a significant number of insect species that do not possess the defining criteria of eusociality are by any other standard of classification clearly social and it is in this sense of the term, that employed by zoologists in general, that larval aggregates of moths, butterflies and sawflies are considered social insects.

The sibling societies of caterpillars exhibit collective behaviors that vary from simple interactions to more complex forms of cooperation.

Social caterpillars exhibit three basic foraging patterns. Patch-restricted foragers obtain all of the food required during the social phase of their larval development from the leaves found in a single contiguous patch or from several such closely spaced patches. The foraging arena is typically well defined by a protective silk envelope or by leaves bound together. On large trees, patches usually consist of the leaves found on a part of a branch, an entire branch, or on several closely situated branches. But on small trees and herbaceous plants the entire host may eventually be enveloped. Although there have been no surveys to determine the proportion of social caterpillars that exhibit each of these foraging patterns, patch-restricted foraging is probably the most common and also the least complex. Well known examples of patch restricted foragers include the Euonymus caterpillar, Yponomeuta cagnagella and the ugly nest caterpillar, Archips cerasivoranus. The fall webworm Hyphantria cunea, is a patch restricted forager during the initial stages of its development.

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