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Black Swallowtails Laying Eggs

6-14-19 black swallowtail 0U1A0073Looking every bit like the Golden Alexander (Zizia aurea) flower buds on which they were laid, the pale yellow eggs of a Black Swallowtail (Papilio polyxenes) are next to impossible to find unless one is fortunate enough to see them in the act of being laid. Members of the parsley family (Golden Alexander, Wild Parsnip, Queen Anne’s Lace, Dill, Carrot) are host plants for most ravenous Black Swallowtail larvae, and thus that is where you will find their eggs. As they eat, the caterpillars absorb toxins from their host plant, which does not harm them but makes them distasteful to avian predators.

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3 responses

  1. Bill On The Hill

    This is fascinating Mary as I had no idea about their immunity to the toxic plants. Mother Nature at her best methinks… Everything in nature seems to have its place.
    I’m curious if this strategy applies to the Eastern Swallowtail as well as currently they are all over my lilacs.
    Off subject here, I witnessed a young red fox this morning, just outside the kitchen window. It appeared to be mouseing & it was blond in color & sported (4) black socks…
    Thanks Mary,
    Bill… :~)

    June 19, 2019 at 9:09 am

    • Love your fox sighting, Bill! I don’t know if the same (toxicity resistance) is true for the Eastern or Canada Swallowtail…but wouldn’t be surprised if it were.

      June 19, 2019 at 10:30 am

  2. Alice Pratt

    I so love the caterpillars, have taken so many photos of them. The eggs show up well on Fennel fronds, my daughter sent me a photo of one that she has, 1st instar, I believe. I’m watching all my parsley & multitudes of ‘rogue’…selfseeded dill…one plant got measured this morning: it’s 3’ 7″! No eggs, yet.

    June 19, 2019 at 1:46 pm

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