The preeminent silk-spinners are the lepidopterous caterpillars. Caterpillars spin silk prolifically and in comparison to other non-eusocial insects build large and relatively complex structures from the material. Moreover, they are the only insects outside of the Hymenoptera and Isoptera to exhibit true collective building behavior involving colony-wide synchronization of activity and periodic shelter expansion.  Some social caterpillars such as Brassolis isthmia and Archips cervasivoranus employ silk to draw the leaves of their host plants into tightly-bound shelters in which they rest between foraging bouts.  But the most impressive structures collectively built by caterpillars, such as the remarkable “bolsa” of the social pierid Eucheir a socialis and the tents of the lasiocampid caterpillars, are made exclusively of silk.

Functions of shelters - The communal shelters of caterpillars are multifunctional, serving to facilitate basking and thermoregulation, molting, and antipredator defense.  They may also serve as communication centers where hungry caterpillars are recruited to food finds.

How silk-shelters are constructed - Little is known of the behavioral mechanisms that give rise to the architecturally distinct, collectively-built shelters of caterpillars.  Unlike the complex, free-form structures of  the eusocial insects, the ultimate shape that the nests of caterpillars take is determined to no small extent by exogenous factors. While colonies may actively select sites prior to the construction of a shelter, or abandon a site that proves inadequate after the shelter-building process has begun, all collectively-built caterpillar shelters are formed either by pulling together plant parts or by spinning silk about a framework of branches and leaves.  Studies suggest that subtle differences in the intrinsic properties of the silks of caterpillars, or the way they are spun, ma y be more important than overt differences in larval motor patterns in accounting for interspecific differences in the form of  the web-nest.

Fitzgerald, T. D., K. Clark, R. Vanderpool and C. Phillips. 1991. Leaf shelter-building caterpillars harness forces generated by axial retraction of stretched and wetted silk. J. Insect Behav. 4: 21-32

Fitzgerald, T. D., K. Clark. 1994. Analysis of leaf-rolling behavior of Caloptilia serotinella (Lepidoptera: Gracillariidae). J. Insect. Behav.7: 859-872

Fitzgerald, T. D. 1995.  Caterpillars roll their own. Natural History Magazine 104:30-37

Fitzgerald, T. D. and J. T. Costa. 1999. Collec tive behavior in social caterpillars. In C. Detrain, J. L. Deneubourg, and J. M. Pasteels (eds.) Information processing in social insects. Birkhauser Verlag, Basel, 379-400