What's in Flight
There is big news in the butterfly world. The population of Monarch butterflies that summer here in our park and up and down the East Coast of America has greatly increased. Tierra Curry, a senior scientist at the Center for Biological Diversity, reports that the number of East Coast Monarchs is now 225 million, up 144 percent from last year. [They are counted while they over-winter on the fir trees of Oyamel, in Mexico]. ‘It is the highest count since 2006 and a thank you from the butterflies to all the people who planted native milkweeds [their host plant].’ Sadly the Monarchs on the West coast haven’t fared as well. Their numbers are in steep decline, Curry reports: ‘The numbers dropped to fewer than 30,000 this year, down from 1.2 million two decades ago.’
Monarch Butterfly on Butterfly Weed (Asclepias tuberosa)
Monarch Butterfly on Zinnia (Zinnia)
July through September is the peak time to see butterflies in the park and around the city. ‘You can see Red Admirals flying along the streets,’ says Hazel Davies, Director of the Butterfly Conservatory at the American Museum of Natural History. ‘They behave like a New Yorker. They are fast flyers, high tailing it down the avenues moving in an erratic fashion dodging traffic. The fast erratic flight is because they need to evade predators whereas the slower, floating and gliding butterflies [such as the Monarchs] tend to be more toxic.’
Red Admiral on Butterfly Bush (Buddleia davidii)
Most butterflies spend their adult life feasting on nectar. But when a butterfly looks at a flower, it sees something far more magical than anything we see. Parts of the flower sparkle and fluoresce with ultraviolet markings. (Photographer Craig P Burrows’ images of flowers, taken under ultraviolet light, hint at what we may be missing with our limited vision). As Davies explains. ‘Butterflies see part of the light spectrum we don’t see. To them the center of a flower is like a landing strip guiding them towards the nectar and pollen.’ Another feature of butterfly vision is they can see nearly 315 degrees around them, which helps spotting predators, food and water sources.
This summer there has been an abundance of Question Marks and Commas in the park. These two butterflies, from the Anglewings group, are named for the tiny silvery-grey question mark or comma on the underside of their wings. The Question Mark is a beauty with crenulated wings, and brownish-black spots on an orangey-red background and a violet rim around its hind wings. Closely related is the Comma, which is slightly smaller in size. Both travel up here in late spring from as far south as Florida. They come to breed, laying their eggs on the leaves of nettles and the American Elm and Hackberry trees. As butterflies, they are unusual in their diet. Instead of sipping nectar, they prefer to feast on tree sap or fermenting fruit, which can sometimes make them appear tipsy or unwilling to fly.
Question Mark markings
Other butterflies flitting around the park this month include the beautiful Swallowtails, which are among the largest butterflies in the world with a wingspan of up to five and a half inches wide for those in India and three and a half inches wide for those in our park.
Eastern Tiger Swallowtail
Eastern Tiger Swallowtail on Butterfly Bush (Buddleia davidii)
At the tinier end of the spectrum are the pretty Eastern Tailed- Blue (about the size of a quarter) and the silvery-blue Summer Azure (the size of a nickel).
Many butterflies have bright showy colors on the upper side of their wings and are dull brown or grey underneath. But the Painted Lady and the American Lady have pretty eyespots and patterns on the bottom side of their wings. These eyespots are to confuse predators,’ says Davies. ‘If a bird pecks at the eyespots, it’s not fatal. A butterfly can still fly if it loses a bit of a wing. But not its head.’ The Painted Ladies are sometimes called Thistle Butterflies as thistles are the favorite host plant for their caterpillars. These butterflies are among the most successful in the world. They can fly up to 30 miles an hour, covering 100 miles in one day during migration.
American Lady Butterfly on Allioum (Allium)
has two eye spots on the lower wing
Painted Lady Butterfly
has four eye spots on the lower wing
Words: Lucie Young
Images: Deborah E Bifulco, Craig P Burrows, Jeffrey Evans, Lucie Young, Kent McFarland, Bob Hall, Lith Gontijo
The Butterfly Conservatory at the American Museum of Natural History opens October 12, 2019
Hazel Davies ‘Inside Butterflies’ book https://www.amazon.com/Inside-Butterflies-Hazel-Davies/dp/1402778740
Craig P Burrows Photography https://www.cpburrows.com
Xerces Society Monarch information https://xerces.org/monarchs/