Not Alarmed but why?

Grkovich, Alex agrkovich at tmpeng.com
Fri Jul 22 13:10:07 EDT 2005


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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