Wednesday, November 23, 2022

Butterfly of the Week: Eastern Steppe Festoon

This week's butterfly is Allancastria (or Zerynthia or Thais) deyrollei, the Eastern Steppe Festoon. This Middle Eastern swallowtail is found in Iran, Turkey, Israel, Jordan, and adjacent countries. Not much has been written about it, perhaps because observers didn't necessarily recognize it as a separate species from the others. The caterpillar has a distinctive look. Photos of the ova and pupa were not found online.

No two photos of adult butterflies in this species look exactly alike, though all of them look more or less like this:



 Photo By Alastair Rae - Flickr: Eastern Steppe Festoon, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=19121640.

Like the other Allancastria, Zerynthia, or Thais species it's a small swallowtail that may have one, two, three, or no separate "tails" on each hind wing. The edges for the forewings can be scalloped or dark-shaded. Wings are whitish with variable blackish and reddish markings. The body is furry and may have bright yellow patches along the sides. The body of an individual photographed beside a ruler was just over 2 cm, or about one inch, long.

Caterpillars have slightly humpbacked shapes and several branch-bristled tubercules, for maximum appetite-suppressant effects on birds.


Like the other species in its genus deyrollei eats the leaves of a vine called birthwort. The caterpillar goes through different skins. Earlier skins are nobblier and simply blackish and whitish. Some individuals with fully developed tubercules are yellowish all over. I found no information online about whether they go through different color phases at different ages, or inherit a tendency to be blackish or yellowish before pupation. Anyway, like most butterflies, they spend more time crawling than they do flying. 

(Symbolism, anyone?)

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