Wild Facts About The Eastern Tiger Swallowtail Butterfly

The Limits Of Pretending To Be Dangerous

• Dark morph Eastern Tiger Swallowtail butterfly females resemble Pipevine Swallowtail butterflies (Battus philenor).
  • Pipevine Swallowtails are unpalatable to many predators, and advertise this characteristic visually through the colors and patterns on their wings.
    • For example, birds quickly learn to associate their black and blue wing coloration with bad taste and possibly sickness (if the birds go so far as to actually swallow the butterflies).
  • In contrast, Eastern Tiger Swallowtail butterflies are neither toxic nor unpalatable to predators.
    • But because predators learn to avoid black and blue butterflies by experiencing ill effects after tasting Pipevine Swallowtails, they also become more apt to avoid attacking dark morph female Eastern Tiger Swallowtails.
  • Called “Batesian mimicry”, the resemblance between the two types of butterflies benefits only the dark morph Tiger Swallowtail females; the legitimately noxious Pipevine Swallowtails gain no benefit for being mimicked.
• So, if mimicking a noxious species gives the dark morph female Tiger Swallowtails protection from being eaten, why aren’t all female Eastern Tiger Swallowtails black and blue?
  • The mimic (the dark morph Tiger) must remain uncommon compared to the model (the noxious Pipevine) for Batesian mimicry to be effective in deterring predation.
  • Otherwise, predators will sample the edible mimics first (because they are more abundant in the landscape), thus diluting the protective benefit for both the mimic and the model.