Movers and Fakers

It’s been a while since I’ve posted any insect photos. But it’s autumn, which means that the Monarchs Are On The Move. A couple of weeks ago I came home and was walking up to the front door when I passed the pair of butterfly bushes (Buddleia davidii) and noticed a rather runty-looking Monarch nectaring.

Then I did a double-take, and thought to myself, “That’s not a Monarch — THAT’S A VICEROY!” (This was one of those odd times when I mentally caption dialog, even the all-caps.) I dashed back to my car to grab my camera, as I didn’t have a photograph of this particular butterfly yet.

The Viceroy (Lepidoptera: Nymphalidae Basilarchia archippus) looks very similar to the Monarch: it’s an orange butterfly with a black body, black margins the wings, and a few white spots in the margins. However, its wingspan is smaller (about 3 inches / 80 mm), and the hindwings have a thin stripe running parallel to the outer margin.

For comparison, here’s a photo of a nearby New England Aster (Aster novi-angliae) with a Monarch (Lepidoptera: Danaidae Danaus plexippus). The wingspan of this butterfly is about 4 inches / 100 mm.

Of course the Monarch is famous for it’s transcontinental migrations. The butterflies heading south to over-winter in Mexico are not those which came up this spring, but rather are their grandchildren or great-grandchildren. In other words, these particular butterflies are migrating to a place where they have never been.

Monarchs & Viceroys are also a famous example of “Batesian Mimicry”. Monarch caterpillars eat milkweeds, and retain the icky poisons in the milky sap of the plants. If a bird or some other animal eats a Monarch, it’s likely to soon throw up, and the bird learns that those orange and black butterflies are nasty! (Of course, that individual butterfly is now history, but its brethren gain some protection from the bird’s learning experience.) The Viceroy catepillars generally eat willow and poplar leaves, so the butterflies don’t have the poisons that would cause such a strong reaction. But the butterflies look similar enough that the Viceroys gain this protection by mimicking Monarchs. Interestingly, we now find that some Viceroy caterpillars do include milkweeds in their diet, which only reinforces the predators’ response to the mimicry.

The New England Aster is a meter-high late-blooming perennial. As a garden specimen, it’s less-than-stellar for its gangly, leggy growth, somewhat floppy habit, and propensity to seed volunteers. As a wildlife habitat resources, it’s fabulous for providing late-season nectar, and mine are always draped in numbers of Monarchs when they make a refuelling stop.

2 Comments

  1. qw88nb88 said,

    20 October 2007 at 14:08

    Excellent question, Chris!

    The patterns of branching wing veination is pretty standardised in insects. Different orders of insects (Lepidoptera, the butterflies, moths and skippers; Coleoptera, the beetles; Odonata, the dragonflies and damselflies; et cetera) have distinctive patterns of wing veination. Even different insect families and genera have slightly different variations on wing vein patterns, which are used to help distinguish and identify them.

    Wikipedia has a nice page on the Comstock-Needham system of pattern and naming of butterfly wing veins.
    andrea

  2. Chris said,

    20 October 2007 at 3:50

    Is the pattern of branching lines in the wings particular to either (Splitting, but never joining from front to back in the Viceroy VS Joining again with other lines in the Monarch.) Or is that just how the two first butterflies happen to look?


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