The red-banded hairstreak is one of our smallest and seemingly most fragile butterflies. Whenever I am fortunate enough to spot one of these tiny flying jewels, I realize that they have little chance of surviving the attack of a predator. Without the benefit of speed or camouflage, they must rely on deception to avoid becoming a meal.
The red-banded is one of a handful of hairstreaks that inhabit my yard. Like the other hairstreaks, the red-banded’s hindwings bear short, slender extensions often referred to as tails or hairs. In addition, two black spots adorn the trailing edge of each hindwing. These spots serve as false eyes. They, along with the projections that look like antennae, are keys to the red-banded hairstreak’s ability to deter predators.
Whenever you look at a red-banded hairstreak perched on a leaf or flower you will notice its hindwings are in constant motion. When one wing goes up other goes down. The constant movement of the butterfly’s wings makes a bird believe it is looking at the head of the insect. As such, when it attacks what it perceives to be the head of its prey, it ends up with nothing more than pieces of the insect’s wings. This gives the butterfly the opportunity to fly away without suffering a lethal wound.
However, Dr. Andrei Sourakov, a scientist with the University of Florida, has conducted experiments that strongly suggest that the hairstreak’s ruse might actually serve to protect it from attacks of another predator known as the jumping spider. When the biologist placed hairstreaks that had their false heads cut off in the same container with jumping spiders, the spiders always attacked the butterflies’ true heads. However, when he placed hairstreaks possessing complete wings in a container containing the predators, the spiders only attacked the butterfly’s false heads.
I am certain the hairstreaks’ behavior dupes birds into striking at their false heads too. However, due to the jumping spider’s greater abundance, it makes sense, that the deception aids the butterflies from fooling spiders more than birds.
This is just another case where research is forcing us to question our long-held beliefs concerning the natural world.