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Eastern Black Swallowtails Laying Eggs

7-23-18 black swallowtail female laying eggs_U1A2171Eastern Black Swallowtail (Papilio polyxenes) butterflies are mating and laying eggs.  The female Eastern Black Swallowtail can appear quite frantic as she visits multiple host plants just long enough to leave a very tiny, spherical, pale yellow egg before heading on to the next plant.  In the wild, Queen Anne’s Lace, Wild Parsnip, Golden Alexander and Poison Hemlock are favorite host plants; in vegetable gardens you frequently find larvae (if you should miss the eggs) on dill, fennel and parsley.  Entomologists have found that host plant odor is one of the cues involved in the Eastern Black Swallowtail’s choice of where to lay eggs.

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5 responses

  1. kissingdogsnet

    Hi Mary,

    Have you ever done a piece on turtles? We have pond across our dirt road here on Cloudland Rd. and in late spring the turtles come up a big distance and cross the road, hopefully not getting hit by cars, some do, and lay eggs. This year a mammoth turtle came *twice* and laid eggs right in our new terrace garden. A huge endeavor of a climb. I expect new borns in September? Why do they do this? Best, Amy

    On Fri, Jul 27, 2018 at 7:34 AM, Naturally Curious with Mary Holland wrote:

    > Mary Holland posted: “Eastern Black Swallowtail (Papilio polyxenes) > butterflies are mating and laying eggs. The female Eastern Black > Swallowtail can appear quite frantic as she visits multiple host plants > just long enough to leave a very tiny, spherical, pale yellow egg befor” >

    July 27, 2018 at 7:40 am

    • Hi Amy,
      Aquatic turtles, like snapping turtles, which I assume your big one was, leave their ponds to seek out sandy soil in which to lay their eggs. It has to be the right consistency for them to dig a hole deep enough to incubate the eggs. You must have sandy soil in your garden! I’d love to photograph the babies when they emerge in September if you feel like giving me a call (802-436-2525). Thanks!

      July 31, 2018 at 5:18 pm

  2. Alice Pratt

    I’ve only seen one beautiful caterpillar on Rue, this year…there are a lot of Rue & Parsley plants here. Several of the host plants…Wild Parsnip causes Phytophotodermatitis….so stay away from that….not sure about Poison Hemlock & Golden Alexander….need to look it up. Queen Annes Lace as well.

    July 27, 2018 at 2:21 pm

  3. Kat Coriell

    Hi Mary, Do EBS’s have two generations a season? Cause I had their caterpillars on my fennel back in mid-June. I had a total of 9 on two (big) plants, but unfortunately I haven’t seen any adults all summer. (pic is from google) Kat, Durham, Maine

    July 28, 2018 at 8:18 pm

  4. Bill on the hill

    Hi Mary… This is a stunningly beautiful butterfly that I have rarely if ever seen on my property. I think I have encountered it in the past, I simply can’t remember if or where!
    Bill Farr… 🙂

    July 29, 2018 at 7:58 am

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