Moths that may mimic spiders

Since it’s Darwin Day, I’ve featured only evolution-related issues, and let’s finish with some amazing pictures by photographer and entomologist Gil Wizen, taken from his eponymous website (with permission; note that he also has a Twitter page and a Facebook page).  (N.b.: the photos are used with permission and cannot be reproduced further.)

In a post called “Petrophilia“, Wizen shows a moth in that genus, trapped in Belize, with some weird markings on its hindwings (captions are from Wizen):

petrophila-sp1

Petrophila sp. in typical resting posture, partially exposing the hindwings.

Why are they there?  We’re not sure, but one clue is how the moth rests:

Many moths rest with their hindwings concealed by the forewings, however these moths, belonging to genus Petrophila, had a unique body posture at rest, exposing only the dotted part of their hindwings. This pattern looked very familiar to me, but I could not pinpoint from where exactly. Then a few nights later one of these moths decided to rest pointing sideways with its head rather than upwards like most moths. And it finally hit me: this moth has an image of a jumping spider on its wings looking straight at you. The mimicry is so convincing that the moth wings even have hair-like scales where supposedly the spider’s head is.

petrophila-sp2

Here’s the moth and its putative “model” (remember, this is a case of Batesian mimicry, in which a palatable mimic apes an unpleasant or dangerous model). Wizen is careful to hedge his explanation:

What I mean to say is that the color pattern on the wings of Petrophila species reminds me of a salticid spider, and perhaps it works the same for other animals as well. There is also a behavioral display that makes the mimicry even more deceiving: the moth moves its wings to mimic the movements of a jumping spider. In search for a second opinion, I turned to someone who breathes and sleeps jumping spiders. Thomas Shahan, who fortunately was around for BugShot, confirmed my suspicion and even came up with an ID for a possible model spider: a female Thiodina sp. And so we went on to find a jumping spider that looked like the one shown on the moths’ wings. In any case, to my untrained eyes it seems that this pattern is common in several moth genera, and in other insects as well.

You can see another moth with a similar pattern at his site, as well as a caddisfly with a salticid-like pattern.

petrophila-sp4-950x447

 

 

11 Comments

  1. Barry Lyons
    Posted February 12, 2017 at 1:39 pm | Permalink

    I’ve said it before and I’ll say it again: this mimicry business is the craziest thing natural selection has to offer.

    Also, what a beautiful moth!

  2. Posted February 12, 2017 at 2:15 pm | Permalink

    I’m uneasy with this one. Is this an example of us seeing Abraham Lincoln in the clouds? The resemblance requires some imagination and does not seem all that strong to me.

    Could something else be going on here?

    I’m wondering what moth predator a jumping spider mimic could be aimed at. A bird? But they munch spiders as readily as moths, I think. Lizard? Similar problem. The worst threats (insect predators and parasitoids) probably don’t have the brains and viewpoint to notice the resemblance. And many probably rely on scent, etc. to find prey.

    • Michael Fisher
      Posted February 12, 2017 at 2:37 pm | Permalink

      Well – In my opinion for every astonishing example of mimicry there should be a handful of half-baked examples of mimicry.

    • wizentrop
      Posted February 12, 2017 at 3:50 pm | Permalink

      Hi, Gil Wizen. I will respond to this question because it is an interesting one. The main target for this apparent mimicry is most likely jumping spiders themselves. They have excellent vision (for an arachnid) and they do respond to the presence of other jumping spiders, trying to avoid confrontations that can cost them their life. Now, whether that is something that actually happens with these moths (= trying to deter spidery predators) is a topic for a series of experiments.
      By the way, my original post mentions that possibility of this being a case of Pareidolia, but you must agree that the fact this very same pattern appears in other insects is intriguing.

    • Tamethyst
      Posted February 13, 2017 at 5:12 pm | Permalink

      Don’t forget, it doesn’t matter what we think it looks like.
      If any predator looks at it thinking “oh, shit it’s one of those fast little jumpers that I can never catch” The moth WINS.

      Who dares wins!

  3. nicky
    Posted February 12, 2017 at 2:52 pm | Permalink

    Whatever objections mentioned above, the visual resemblance (from the side) is absolutely striking, stunning even. I suppose that birds are not the only predators of moths. Especially since the resemblance is from the side, we suspect it is aimed at predators of the same size or level as the moths.
    Since we are not as ‘smell conversant’ as most mammals and many arthropods, we may miss a lot of ‘odourous’ mimicry. Aposematic or Batesan smells? Is there actually any research in the smelly field?

  4. Mark Sturtevant
    Posted February 12, 2017 at 4:50 pm | Permalink

    I see the resemblance, especially in the 3/4 view, and this goes along with the posture it uses in its wings. It could well be mimicry, although I am not 100% convinced right now.

    • nicky
      Posted February 12, 2017 at 7:33 pm | Permalink

      Strange, I find it absolutely convincing mimicry, even half of the leg are visible.
      The wings are also held in a big peculiar angle. The more I look the more it resembles the jumpingnspider: autohypnosis?

      • nicky
        Posted February 12, 2017 at 7:56 pm | Permalink

        Sorry, typos: legs not leg, a bit not a big, and jumping spider not jumping spider.
        That barklouse is also very convincing.

  5. Posted February 12, 2017 at 7:36 pm | Permalink

    Is there good reason to think that jumping spiders would trigger avoidance by the moth’s predators, presumably birds? Do they taste bad? And I cannot compare size by the pictures but I know jumping spiders are quite small. Wouldn’t the moth mimic be a bit large?

  6. Mike
    Posted February 13, 2017 at 7:34 am | Permalink

    Beautiful Moth,and the Spider is very convincing.


One Trackback/Pingback

  1. […] Source link […]

Post a Comment

Required fields are marked *
*
*

%d bloggers like this: