Not Alarmed but why?

[Bill Cornelius]

Two ways it seems that butterflies hide are camouflage & asymmetry. They 
attract attention by being symmetrical & avoid recognition by being 
asymmetrical. They like to point one wing directly at the viewer & hold 
the other at a low angle. I'm curious whether some sections of their eye 
has qualities that instigate that behavior, like

1): movement over the shoulder that shows up in several eye cells would 
mean a large object. If it keeps the same aspect to the butterfly, and 
shows up in adjoining eye cells, would mean the object is moving towards 
something in the butterflies immediate vicinity (butterfly or not) & 
could mean trouble. Like mate chasing or chrysalis formation, would take 
no brains to evolve (givin an infinite number of offspring) but would 
have survival value.

2): movement visible in both the butterflies eyes (both sides) might 
cause it to suddenly spread it's wings. If the movement is caused by a 
creature, with binocular vision, the markings on the wings would 
suddenly move apart toward the periphery of the viewers vision & would 
appear to be jumping at the viewer, like the mouth of a frog, snake or bird.

Some kind of maneuver might be thought up to test the idea of eye cells 
causing different responses. (Maybe we could become invisible to them. 
mirrors maybe or a hidden light source?)

Bill



    The Satyrids are particularly notorious for this sort of thing (i.e.
    rotating to make themselves less visible...)

    Another curious behavioral phenomenon that I have noticed in
    tropical Satyrids is this: Since they tend to occur in partly or
    fully shaded environments to begin with, they are already difficult
    to see and follow in flight...But, in places where they are very
    numerous, and where there will be multiple species within a
    givenarea (such as in a partial clearing in the woodland), as you
    approach, they (and this can be dozens of specimens, several
    species) will at first all be at rest. As you draw closer, they will
    all take flight at almost precisely the very same moment, and in
    different directions, in and out of cover...Then, after a short
    period of perhaps 5 to 10 seconds (no longer), they will all alight,
    almost on cue. The result of this is, of course, to bewilder the
    Lepidopterist, making it exceedingly difficult to focus on any
    particular specimen...This really causes quite a significant level
    of confusion. I would suspect that potential predators would be
    similarly confused...

    Alex

          -----Original Message-----

          From:   owner-leps-l at lists.yale.edu
    [SMTP:owner-leps-l at lists.yale.edu] On Behalf Of The Walkers

          Sent:   Friday, July 22, 2005 11:35 AM

          To:     leps-l at lists.yale.edu; fnkwp at uaf.edu

          Subject:        Re: Not Alarmed but why?

          Great thought.  When I was doing research in robot vision, we
    developed 1st derivative and 2nd derivative motion detector
    algorithms, creating a 2-D visual display mapped with highlighted
    regions where changes in an objects position and acceleration were
    detected.  Of course, this first required that we perform reliable
    object recognition over the visual field, which is a hard enough
    problem to solve.  Fun stuff.  The bottom line is that we know
    little about what insects actually "see".  One thing I have noticed
    is that resting butterflies will often position themselves so that I
    can't see their hindwings, making it virtually impossible to make a
    positive id without netting them.  When I attempt to move my head
    (slowly and with constant velocity) around to catch a better
    glimpse, the alighted butterfly will often rotate itself on the
    flower or branch, maintaining its _perpindicularity_ with respect to
    the direction of my gaze, continuing to make itself virtually invisible.

           

          Mark.

           

          -------Original Message-------

           

          From: fnkwp at uaf.edu <mailto:fnkwp at uaf.edu>

          Date: 07/22/05 01:55:07

          To: leps-l at lists.yale.edu <mailto:leps-l at lists.yale.edu>

          Subject: Re: Not Alarmed but why?

           

     > Many times, when I spy the lep, I stop moving my head,

     > and the lep takes off!  Clearly it knows it has been spotted.

           

          It is possible that all the butterfly is doing is reacting to the

          second derivative of the motion of your head--that is, to the

          rate of change of the speed with which your head moves. Try

          stopping the movement of your head gradually rather

          than suddenly, and see if that helps.

           

             Ken Philip


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