2017-10-01 / Community

Butterflies have evolved to survive severe storms

BILL RHODES


Zebra longwing butterfly on an allamanda cathartic flower. Zebra longwing butterfly on an allamanda cathartic flower. On any sunny day, visitors to the Conservancy of Southwest Florida will see a variety of butterflies in flight. A short walk to the butterfly garden, with its native flowering plants, generally results in sightings of bright yellow, fast-flying orange barred sulphurs (Phoebis philea), or the orange Gulf fritillary (Agrualis vanillae), which sports brilliant silver spangles on the underside of its wings.

Walking a bit farther along the trail, into the shade, hikers often will see a black and yellow striped butterfly lazily flitting about only a few feet from the ground. This is the zebra longwing (Heliconius charithonia), the state butterfly of Florida.

You might wonder why it is that the zebra, unlike the other butterflies, flies so slowly and awkwardly, considering butterflies make great meals for birds. It is a member of the subfamily Heliconiinae, a group of subtropical and tropical butterflies known for their toxicity and bitter taste, gained in their adult stage from the pollen they eat. Consequently, they don’t need to be very fast to avoid predation — they simply don’t taste good.

Many may also be wondering if, after the devastating impact of Hurricane Irma, butterflies will be as locally abundant at the Conservancy and elsewhere as before. Luckily, butterflies are remarkably tolerant of storms, even powerful hurricanes. As caterpillars, they have a series of prolegs, not true legs, on their abdominal segments, each equipped with multiple tiny hooks that provide a very strong grasp on almost any surface. In front of these prolegs are six regular legs, and all together, they can grasp amazingly tightly. With their tubular bodies and low profile these caterpillars are generally safe from even the highest winds.

Adult butterflies, which seem far more fragile, actually also do well. A few hours before a storm hits, they seek shelter in cracks and crevices in rocks, trees or buildings. Others will go low to the ground amid tall grasses and weeds and cling there. These adults also will orient themselves with their wings folded above their bodies, so that the narrow portion is facing into the wind, providing less surface area and allowing them to withstand higher gusts while swaying with the grasses. The highest risks to butterfly populations from a hurricane are the destruction of their habitats by wind or flooding of their host plants by salt water, resulting in the larvae having nothing to eat.

Butterflies have evolved over millions of years to survive the worst nature can throw at them, so you can rest assured that if you take a walk to the Conservancy’s butterfly garden or along one of our trails, you are sure to see flapping wings and flashes of bright color along the way.

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