Ames Free Library

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A Glimpse of Nature - Eastern Tiger Swallowtail

See what’s happening on the grounds of the Ames Free Library or nearby areas with “A Glimpse of Nature.”  Offered by Lorraine Rubinacci, the library's resident naturalist, this weekly photo blog is a gentle reminder to enjoy the wonders that surround us.


A Glimpse of Nature - "Eastern Tiger Swallowtail"

Butterfly + milkweed = Monarch.  Nope!  This beautiful, striped butterfly is an Eastern Tiger Swallowtail.

It’s easy to identify:  black “tiger” stripes on yellow wings; long barn-swallow “tails” on the hindwings.  And it’s big! It’s wingspan can exceed five inches.  Females, like the one in this photo, have a blush of blue on their hindwings. Their slow, graceful flight makes them recognizable even from a distance.

This Eastern Tiger Swallowtail is sipping nectar from common milkweed, but adults feed on a variety of garden and native flowers including bee balm and Joe Pye weed. The caterpillars prefer the leaves of hardwood trees, especially black cherry, ash, and our friend, the tulip tree.  The need for host trees and herbaceous nectaring plants often brings this species to forest edges, where both can be found, places like the Ames Free Library’s campus.

For many insects, including this butterfly, adulthood is a brief stage of life.  If you want to expand your observations, look for a bright green egg on the leaves of its host plants.  Or, perhaps you can find the young brown and white caterpillars that look like bird droppings.  As they grow, the caterpillars turn green and develop a different defense mechanism:  scary “eyespots.”  All of these stages are well illustrated in the article, How to Raise Eastern Tiger Swallowtails - Butterfly Life Cycle Photos.”

But don’t delay.  Like other natural phenomena, this insect’s life cycle has its season.  According to a survey called the Massachusetts Butterfly Atlas, “The peak flight seems to coincide with the blossoming of the common milkweed . . . .” Milkweed flower buds are starting to open along the library’s intermittent stream and throughout our area.

At the Library

Butterflies through Binoculars: The East

by Jeffrey Glassberg

A Place for Butterflies

by Melissa Stewart

Butterlies of North America

by Jim P. Brock and Kenn Kaufman


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