Which Female Butterfly has Two Forms?

This week’s creature feature is the Eastern Tiger Swallowtail Butterfly, one of the most commonly seen butterflies in the eastern US and Canada. With a 4-5 inch wingspan and beautiful yellow and black wings, this butterfly is almost as well known as our orange and black Monarch. Here are some things you may not know about this lovely butterfly:

1. The fact that I think is most interesting is that the female of this species is dimorphic, meaning she has two forms. She can be yellow and black like the male, or she can have a black form that resembles the Pipevine Swallowtail.

In her yellow form, she has more blue than the males.

2. Eastern Tiger Swallowtails get their names from the two tails on their hind wings that resemble the tails on the birds by the same name. Also, their fore wings are striped yellow and black, like a tiger’s stripes.

3. As caterpillars, they look like bird poop. This, as you can imagine, might make them less appealing to some animal like a bird looking for a meal. After they have eaten and molted several times, towards the end of this stage of their life, they resemble a snake, with fake eye spots. Click here to read the post about this.

4. Caterpillars feed on a variety of host plants including poplar, black willow, red maple, ash, and elm. Female Tiger Swallowtails lay their eggs on the undersides of leaves on these trees.

5. The first meal of the caterpillars is their egg shell.

6. Adult butterflies do not eat, they drink nectar from flowers using their long tube-shaped tongue–called a proboscis– (pronounced Pro-bah-sis. The c as the end of the word is silent.)

7. Like all butterflies and moths, the wings of Eastern Tiger Swallowtails are covered with thousands of tiny scales. When you touch a butterfly and have a dust-like substance on your hands afterward, these are some of the scales that have rubbed off. It is best not to touch butterfly wings for this reason.

8. Tiger Swallowtails have two fake tails on each of their hind wings. If a bird grabs them from this end, they can lose these and still fly.

9. Eastern Tiger Swallowtails live about a month.

10. The chrysalis of the Eastern Tiger Swallowtail looks like a part of a tree. When it emerges from this, it will have wings and be an adult–so much different looking than when it went into this stage.