These little guys were tiny enough to overlook easily, but bizarre and striking on close inspection. I am informed that the peacock like ‘plumes’ on the ends of these insects are likely to be made from cast skins or even ‘tubes’ of excrement. The beauty of nature.
Insect larvae can be tricky to identify, but general consensus among entomologists I showed this to, is that these are some sort of chrysomelid (leaf beetle) larvae. The family Chrysomelidae is a large and diverse group of small to medium sized beetles which take on a variety of forms, but tend to be found feeding on plants in both the larval and adult forms. These particular larvae appear likely to be skeletonizing leaf beetles*, so named from the manner in which they feed off the plant, and the leaf ‘skeleton’ left behind. Like many insect larvae, these appear to be somewhat gregarious, as I observed them mostly in small groups.
*Update: Laura suggests that these should be Cassidinae, or the larvae of tortoise beetles (see comments). Tortoise beetles are fabulous little critters, so I’m thrilled to learn that their babies frequently make dramatic poop structures.