Swallowtail Butterflies

Several weeks ago, we had orange and black Monarch butterflies migrating through the Front Range. They seem to have moved on.

But we’ve still got big butterflies in the area — yellow and black swallowtails. I’ve seen two different types of swallowtails. The western tiger swallowtail is lives along waterways and in woodlands, as well as suburban areas. It’s caterpillers eat aspen, cottenwoods and green ash. The eastern version of this butterfly …. hmmm…. lives in the east? That’s all I’ve found to separate the two.

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Western tiger swallowtail on Canada thistle.

The other species of swallowtail that I commonly see in the west Denver area is the two-tailed swallowtail. Predictably, it has two tails.  These butterflies lay their eggs on green ash and chokecherry, although the adults evidently like the nectar from our milkweed plants.

Two-tailed swallowtail
Two-tailed swallowtail on milkweed.

It’s a hard life being a butterfly. This poor guy has survived a lot.

Damaged two-tailed swallowtail butterfly on milkweed.

Swallowtails lay their eggs on their preferred plants. The eggs hatch out into caterpillers, which proceed to feed on their host plants. When winter comes, these larva spin a chrysalis (cocoon), in which they overwinter.

Unlike Monarchs (Monarch Butterfly Migration) or Painted Ladies (Painted Ladies migrate across North America! Painted Ladies Part Two), swallowtails only produce one generation a season. The adult swallowtails emerge in May and June, and continue to be active in the same area through August, feeding on plant nectar, as the butterflies above are doing. Sometime in the summer, they lay their eggs.

6 responses to “Swallowtail Butterflies”

  1. They are so spectacular, not only for their size but for that distinctive coloring and tail.

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  2. I always feel bad for those with tattered wings. How much harder does that make their lives?

    Nice photos!

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  3. Pat Law Avatar
    Pat Law

    Great blog, wonderful pictures and interesting information. I’ll share with The Ladies, and I”ll tell them about your 4 foot milkweed plant, growing through the concrete crack.

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  4. Beautiful pictures!!

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    1. Glad you liked them! I only recently started paying attention to the butterflies around me, and am surprised at how many different types I see. These guys were just in our backyard.

      Liked by 1 person

  5. […] Western Tiger Swallowtails also like streams, but also venture into open grasslands. Their caterpillars eat the leaves of trees and shrubs like cottonwood, birch alder, chokecherry, willows and wild plum. The adults, like many butterflies, drink nectar. https://amylaw.blog/2018/07/18/swallowtail-butterflies/ […]

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