Not Alarmed but why?

[The Walkers]

Yes, I have experienced the same phenomenon on many occasions.  The
triggered random (chaotic?) flight is a thing of beauty, but it is virtually
impossible to net a target individual in the presence of such confusion. 
Perhaps it would make sense to merely swing and see what your net comes up
with, but I don't think I've ever attempted it.  Instead, I become part of
the dance - albeit an awkward and graceless part - as I jerk back and forth
in indecision.  Still, there's no better feeling than to be in the middle of
such a thing.  It becomes easy (out of frustration?) in such circumstances
to simply drop the net and watch the spectacle.

Mark.
 
-------Original Message-------
 
From: agrkovich at tmpeng.com
Date: 07/22/05 10:28:45
To: xvermontrz at cox.net; leps-l at lists.yale.edu; fnkwp at uaf.edu
Cc: TILS-leps-talk at yahoogroups.com
Subject: RE: Not Alarmed but why?
 
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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