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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 Reserva Nacional Tambopata, Peru – The art of deception: can gossamer-wing butterflies, Arawacus sp., dodge lethal attacks?


At the right end of this butterfly are its head, thorax, and abdomen, vital parts that are targets for a predator’s attack. At the left end of the butterfly at the tips of the hindwings are two white–tipped, antennae-like tails, a head-like rounded dark patch, and a small white eye spot that combine to create a false head intended to misdirect a predator’s attack.


After a brief respite from Old Man Winter, the weather has again turned chilly in Maryland so let’s head to the rainforest along the Tambopata River to see how another clever insect uses the art of deception to avoid being eaten by a predator. In recent episodes we learned how skipper caterpillars clipped leaves to hide their feeding activities, how leaf-like katydids evolved to blend in with their surroundings, and how many walking sticks, grasshoppers, and mantises depend on body form, color, and behavior to mimic branches or twigs to escape detection from predators. This week we will discover how a beautiful Neotropic butterfly foils would-be predators.

Many gossamer-wing butterflies, Lycaenidae, have unusual appendages at the rear tips of their hindwings. These appendages strangely resemble antennae found on the head of a butterfly. I happened upon one such gorgeous gossamer-wing lapping food from a leaf on a small rainforest plant. At first glance, I was confused as to which end of this creature was the head and which end was the tail. You see, the antennae-like filaments at the rear end of the butterfly slowly moved up and down in much the same fashion as antennae might. The rounded lower wing tips, dark coloration at the base of the filaments, and an eye-like white patch combine to resemble the head of an insect. Converging dark wing bands directed my attention on the rear end rather than the front end of the butterfly.


Watch as this beautiful butterfly moves about the leaf gently waggling antennae-like filaments on the false head at the tip of its rear end. Will the ruse be sufficient to foil a predator’s attack?

How does the visage of a head at the rear end help the butterfly survive a predator’s attack? This clever visual deception is described brilliantly by Adrian Hoskins his web site below. Many butterfly-hunting predators direct their strike at the meaty anterior end of a butterfly. Not only is the food better in these parts than in the wings, but by disabling the head or thorax the chances of the butterfly escaping an attack approach nil.  A so-called “dummy head” at the rear end is thought to direct attacks by predators to the tips of the butterfly’s wings, allowing it to make good its escape while dodging a lethal bite to vital body parts such as head, thorax, and abdomen, at the opposite end. Once again trickery through morphology and behavior help clever insects survive in the treacherous tropical rainforest.


The wonderful book “Insect Defenses” by David Evans and Justin Schmidt, and Adrian Hoskins’ amazing website “Learn about Butterflies” about all things butterfly, were used to prepare this episode. To learn more about the Arawacus gossamer-wing featured in this episode please visit Adrian Hoskins’ website at this link: