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Bug of the Week is written by "The Bug Guy," Michael J. Raupp, Professor of Entomology at the University of Maryland.

Destination Puerto Maldonado, Peru: Skipper caterpillars, Hesperiidae, play hide and seek with predators in the rainforest


Contrasting yellow bands against an umber background may warn predators of the unpalatability of this skipper caterpillar.


Last week we stopped in southern Florida to visit beautiful Atala butterflies feeding on cycads in urban gardens. This week we continue our tropical adventures and head about 3000 miles south to the Amazon rainforest near Puerto Maldonado, Peru. A creepy nighttime walk in the rainforest reveals delights unseen by day. Along a jungle trail brightly colored larvae of skipper butterflies hastily devour leaves of rainforest plants. The speed at which these eating machines demolish foliage is remarkable. Larvae will gain more than a thousand times their birthweight by the time they complete development and form a chrysalis. But they must hurry. Keen-eyed reptiles, including ones with feathers, will be active come daybreak.


Wonders unseen by day are revealed at night on a walk in the rainforest. Watch as this skipper caterpillar gobbles leaves of Inga then eliminates evidence of its presence by clipping the remainder of the leaf from the branch. Listen as birds and howler monkeys greet the arrival of dawn.

 Defenses of skipper caterpillars to avoid the jaws of predators are clever and varied. Like Atala caterpillars we met last week, larvae of many species of skippers, including those in the genera Astraptes and Elbella, sport brilliant colors and contrasting bands and blotches that may advertise their unpalatability and warn predators not to mess with them lest they suffer an unhappy meal. Warning coloration alone may not work for all caterpillars against all enemies and behavioral defenses may be employed to ensure that caterpillars live another day. One way inquisitive bug geeks locate hard-to-find insects is to observe so called “artifacts” they leave behind, products of activities such as feeding. Artifacts include honeydew produced by sucking insects like aphids or damaged leaves caused by weevils we met in previous episodes.


While their larvae feed at night, gorgeous butterflies rest beneath leaves in the rainforest.

As you might guess, birds also use clues, such as damaged leaves, to locate juicy caterpillars that serve as a major source of protein for themselves and their young. In the game of hide and seek, clever skipper caterpillars have evolved behaviors to escape death from visually astute predators. After consuming as much of their leafy meal as possible, skipper caterpillars may sever the uneaten portion of the leaf from the plant by chewing through the petiole. The damaged leaf drops to the ground, thus eliminating the clue that a caterpillar is on a branch nearby. Ah, but these crafty caterpillars have one more trick to help foil detection by those that would eat them. Using dexterity and a small amount of silk, skipper larvae like the ones in this episode roll the margin of a leaf to form a small wrapper that serves as a shelter from the searching eyes of predators. We observed the construction of hiding shelters in other species of butterflies including the gorgeous spice bush swallowtail and silver spotted skipper right here in Maryland. In the never-ending battle for survival skipper caterpillars are among the most adept in the game of hide and seek.


Who’s that hiding inside the rolled leaf?


Bug of the Week thanks the crew of the Posada Amazonas for providing the inspiration for this episode. The wonderful book “Insect Defenses” by David Evans and Justin Schmidt was used as a resource for this episode. Many thanks to Bob Roberts, Olaf Hermann Hendrik Mielke, and John Burns for help in identifying skipper larvae featured in this episode.