Gregarious Caterpillars on a lime leaf 30 Jul 2013 18-42

Gregarious Caterpillars on a lime leaf 30 Jul 2013 18-42

Observation - Gregarious Caterpillars on a lime leaf 30 Jul 2013 18-42. Description: This mass of tiny caterpillars evidently hatched from the eggs seen on the lower leaf surface in the 2nd photo, then migrated to the top surface of the leaf and grazed it right down to the lower surface. Most of them then appear to have retreated to the l

This mass of tiny caterpillars evidently hatched from the eggs seen on the lower leaf surface in the 2nd photo, then migrated to the top surface of the leaf and grazed it right down to the lower surface. Most of them then appear to have retreated to the lower surface of the leaf again, leaving just a few stragglers remaining on the top surface.

I'd love to know what they are!