Research grade species #1240: Red- banded Hairstreak
About 5 minutes after I gloomily proclaimed that future generations will know no butterflies but the ubiquitous and invasive cabbage white, I encountered this tiny beauty. I was letting my environmental pessimism bring down an otherwise upbeat pollinator survey. We had wandered through a few different habitats inside the bounds of the zoo fences, and were looking at the insects visiting the blooms in the Organic Garden section. It was a bit overgrown, owing to a year of pandemic-related neglect followed by a general shifting of priorities by the very busy Horticulture department.
The hairstreaks are small quick butterflies with wingspans of 3 or 4 centimeters, shining metallic blue or bronze on the backs of the wings. Underneath, the wings are lines with delicate markings (hairstreaks) ending with "tails" which, often accompanied by eyespots, are actually false fronts. The tails confuse predators into attacking the wrong end of the insects, buying critical milliseconds to escape. This species also has the nominative red bands across the bottom of all four wings, which might help draw attention to the eyespots and false antennae.
The larvae are slug caterpillars with a hunger for a variety of mostly subtropical plants, from mango to sumac. The eggs are laid on fallen leaves around the host plant--another species that benefits from leaves being left in place, not blown or raked into bags. Bugguide lists the limit of the Red-banded Hairstreak's northeastern range as Connecticut, iNaturalist users have pushed that up into Massachusetts. In fact, with the exception of observations on Plum Island and out on the Cape, Boston is the northeastern-most habitat of this creature. And not to dip back into eco-gloom, but that range is bound to expand with anthropogenic climate change.