It’s all in the spots

White Admiral or Red-spotted Purple — do those sound like the same butterfly?  Well, they are, strangely enough.  Although once considered separate species, they are in fact the same one that occurs from Alaska to Texas through-out the central and eastern U.S.

In the north they look like this, and are recognized as White Admirals.

By D. Gordon E. Robertson (Own work) [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0) or GFDL (http://www.gnu.org/copyleft/fdl.html)], via Wikimedia Commons

By D. Gordon E. Robertson (Own work) [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0) or GFDL (http://www.gnu.org/copyleft/fdl.html)%5D, via Wikimedia Commons

In the southern part of their range they look like this, and are recognized as Red-spotted Purples.

Note absence of white spots and iridescent blue color on the upper surface of the wings

Note absence of white spots and iridescent blue color on the upper surface of the wings. The underside of the wings have many orange spots. Taken two years ago in my backyard.

The other day, an individual that truly looked like an intermediate between these two forms showed up to have a drink from the milkweed flowers.

Some white spots definitely visible, along with a lot of orange on the underside of the wings.

Some white spots definitely visible but not as large and well delineated as the northern White Admiral.  There is also a lot of orange on the underside of the wings.

But also some of the iridescent blue color, especially on the hind wing.

But also some of the iridescent blue color, especially on the hind wing.

Wikipedia calls this species polytypic.  This intermediate coloration seems appropriate for an individual that is somewhat in the middle of the entire geographic range where you would expect hybridization of the northern and southern color morphs.

The Red-spotted Purple form is actually a mimic of the poisonous Pipevine Swallowtail, so there may be advantages to keeping some of that southern coloration in this mid-latitude geographic area.

5 thoughts on “It’s all in the spots

    • That just keeps life interesting for the taxononmists, and now that they have a new set of tools (DNA analysis), they can revise the species names and confuse us all!

  1. Fascinating, Sue, to see such a hybrid (and amazing that you could notice that this butterfly was different). We have the Red-spotted Purple butterflies in my part of Virginia–I have never seen a White Admiral.

  2. Hello Sue, I realised I hadn’t heard from you for a while and I just found out I wasn’t following Back Yard Biology, which is shockingly remiss, but I’ve now rectified that.

    Your butterfly pictures are spectacular, lovely portraits. The northern white admiral is interesting, is it ‘Limenitis camilla’? It looks a lot like it. If so, it’s the same species we have in the UK. But we don’t have any other polymorphs here.

    • Hi Finn, I just realized you somehow dropped off my “follow” list as well, but I have corrected that. In the U.S., the White Admiral is Limenitis arthemis, so must be a close relative of yours.

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