June 9, 2013

Tiger Swallowtails back to fly into face of danger

It’s early June and the Tiger Swallowtails have reappeared. They seem to appear from thin air in the most unlikely places.

Since I was a child I’ve always imagined they carry secret messages. Their large size, bright colors and twitchy flight pattern make them seem as musical as birds but it’s their silence that exaggerates the surprise of seeing one.

The Tiger Swallowtails are already well along in the business of mating and producing two or three generations before the end of summer. Unlike the Monarchs that return from exotic places in Mexico, the Tiger Swallowtails stay in northern forests in winter. In the fall, each caterpillar will form a hard chrysalis that it will hang from a twig, branch, roof, swing set or other surface by a thread-like attachment. In the chrysalis they transform again and in spring emerge as adults. The adult butterfly will live 3 to 4 weeks if it doesn’t succumb to predators.

Butterfly wings are truly spectacular inventions of nature. Although they grow in two pairs, the fore and hind wing on each side become attached during flight and function as one wing.

The wings are formed of thin, almost transparent membranes made of chitin, like human hair and fingernails. Over the membranes thin scales form.

The website explains, “Besides being responsible for the magnificent colors characteristic of butterflies, scales also protect and insulate the insects and aid in the flow of air along their wings as they fly. Scales also may help the butterfly to soak up the heat that flying requires.”

Special scent scales of male butterflies emit pheromones that attract females.

Survival for all butterflies is tough and bad weather makes it tougher.

Before the weather forecast is even announced, butterflies face a high mortality rate because so many predators feed on them. Predators include birds, rodents, reptiles, amphibians, viruses and even other parasitic insects. Despite the odds, Tiger Swallowtails are not considered threatened as a species.

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