Giant Butterfly Invades Adirondacks!

Giant swallowtail butterfly

On an early August Saturday, a creature the size of Tinkerbell fluttered nonchalantly over the oregano. It alighted over and over, nectaring on the pale purple flowers for several minutes. Then it flapped toward me and lingered in front of my face before rising and disappearing over the cedars.

The butterfly’s wings were dark on top, with a bold yellow stripe across the shoulders and tell-tale swallowtail paddles extending from the bottom. Other than size—its wingspan was as wide as my outstretched hand—what struck me most was its unhurried flight.

It was unlike anything I’d seen in the Adirondacks, so to the guidebooks I went. It sure looked like a giant swallowtail, the largest butterfly in the United States. But that species is usually found in the South. It took a YouTube video of its floppy flight to seal the ID.

Another giant swallowtail flapped through the yard in late August. In the meantime, people have been talking about the dazzling visitors.

“Giants are tropical and southern region butterflies. I have seen them in Texas and Mexico. But they have been making northerly incursions the past couple of years, even into Canada,” Sheila Rosenberg e-mailed. She is a seasonal resident of Paul Smiths and a participant in Northern New York Audubon’s annual butterfly count.

Rosenberg did not see a giant in the wild this summer, but she saw a captive specimen at the Butterfly House at the Paul Smiths College VIC, one of several observed on the property in the past two months.

A Harvard Forest study published last month in the journal Nature Climate Change reports that northern-range butterflies are declining in Massachusetts and being replaced by warm-temperate and subtropical species such as the giant swallowtail (Papilio cresphontes) and zabulon skipper (Poanes zabulon).

A warming climate as well as changes in land use and plant distribution (some butterflies are switching from native host plants to invasive species) all influence what lives where.

Sue Grimm Hanley, manager of the VIC’s Butterfly House, found the caterpillars of another central-Adirondack rarity, the common buckeye, in July.

She says there is still a buckeye flying around the netted house as well as a chrysalis that hasn’t opened. The Butterfly House will be open sporadically this week before closing for the season.

While butterflies feed on the nectar of a variety of flowers, butterfly watchers are trying to figure out if giant swallowtails will lay eggs in the Adirondack northern forest. Caterpillars are particular, and the main host plant of the giant swallowtail is a citrus-family tree called prickly ash, which does not grow at the central Adirondack elevation and latitude. Yet.

In July giant swallowtail caterpillars were discovered on a prickly ash at the Montreal Botanical Garden, the first time the species had visited that site.

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