rp@juno.ll.mit.edu (Richard Pavelle) (03/06/91)
I have been struck by the random flight (fluttering) of moths and butterflies. An explanation could be that the behavior would help avoid capture. But the flight may appear more random than it is. Does anyone have any thoughts on this? --
ajpierce@ulah.med.unc.edu (Andrew Pierce) (03/07/91)
In article <1991Mar5.195259.20804@xn.ll.mit.edu> rp@juno.ll.mit.edu (Richard Pavelle) writes: >I have been struck by the random flight (fluttering) of moths >and butterflies. An explanation could be that the behavior would >help avoid capture. But the flight may appear more random than >it is. Does anyone have any thoughts on this? I heard a long time ago, that the movement of moths overall is not random. I don't know how one would correlate overall directional motion with short-scale random motion, but it would be an interesting thing to address. That the overall movement is directional can be shown by the way moths are attracted to lights at night. Supposedly the reason for this is that the moths have some sort of guidance system which relies upon parallel rays of light. With sunlight or even moonlight, this is a pretty good approximation since the lights are relatively far away. With an artificial light though, the light rays are NOT parallel. The moths however don't realize this and as a result spiral in towards the light source. Does anyone have any information on this being true or not, or are moths just attracted to bright lights for some reason? -Andy
jahayes@miavx1.acs.muohio.edu (03/08/91)
In article <1991Mar5.195259.20804@xn.ll.mit.edu>, rp@juno.ll.mit.edu (Richard Pavelle) writes: > I have been struck by the random flight (fluttering) of moths > and butterflies. An explanation could be that the behavior would > help avoid capture. But the flight may appear more random than > it is. Does anyone have any thoughts on this? > Yes, but I stole them :-). A couple of my colleagues at the University of Texas, Bob Srygley and Peng Chai, published a paper in (I think) the American Naturalist a couple issues ago on this very subject. Srygley and Chai (SR hereafter) hypothesize that tropical butterfly flight patterns are correlated with predation risk and aposematic coloration/distaste. Butterflies that are tasty have to fly erratically and quickly, and also tend to spend most of their time in the shade, while those that are distasteful to predators lumber about in placid regular wingbeats in the sunshine. It's a remarkably good fit to the observed species distributions and flight patterns of the butterflies in question. Srygley used videotapes of bfs in flight and then digitized every tenth frame or so to get sorta stroboscopic views of flight paths. Pretty neat stuff. I helped with the statistics, but other than that I have no connection with the work, I just think it's neat. Regards, Josh Hayes, Zoology, Miami of Ohio jahayes@miavx1.acs.muohio.edu
kuento@kuhub.cc.ukans.edu (03/08/91)
> I heard a long time ago, that the movement of moths overall is not random. That's correct - in fact, there are no self-propelled organisms in which movement is truly random, except for certain "escape" behaviors in various organisms (that is, random movement is only a temporary and very special condition). Even bacteria do not move randomly. > address. That the overall movement is directional can be shown by the way > moths are attracted to lights at night. Supposedly the reason for this is > that the moths have some sort of guidance system which relies upon > parallel rays of light. With sunlight or even moonlight, this is a pretty > good approximation since the lights are relatively far away. With an > artificial light though, the light rays are NOT parallel. The moths > however don't realize this and as a result spiral in towards the light > source. Does anyone have any information on this being true or not, or > are moths just attracted to bright lights for some reason? > -Andy Moths and many other insects are attracted to bright lights because they try to keep the light *above* them as they fly (this is normally where the moon will be in their field of vision). Artificial lights are disorienting because when the insect shifts around so the light is "up" in its field of vision, it ends up spiralling in. If you ever look closely at a moth circling, you'll notice that the moth is tilted strongly sideways, perpendicular to the long axis of the light source. If it were simply being confused by parallel vs. non-parallel lights, only the yaw would change, not the roll, and they would circle while remaining essentially level. -------(please include "DY" in subj header of mail to this user)-------- Doug "Speaker-To-Insects" Yanega "UT!" Bitnet: KUENTO@UKANVAX My card: VIIII The Hermit (Snow Museum, Univ. of KS, Lawrence, KS 66045) "Bleating and babbling we fell on his neck with a scream" - P.F., Animals
arf@gagme.chi.il.us (jack schmidling) (03/15/91)
Article 4097 (15 more) in sci.bio:
From: kuento@kuhub.cc.ukans.edu
Subject: Re: moth flutter
>Moths and many other insects are attracted to bright lights
because they try to keep the light *above* them as they fly
(this is normally where the moon will be in their field of
vision). Artificial lights are disorienting because when the
insect shifts around so the light
the long axis of the light source.
ARF says:
Perhaps the key lies in the above but I fail to see it.
Try explaining it using flourescent tubes in various
attitudes and then with a point source.
I have visions of a moth flying on its side, endlessly
circling but never having to get near the light to keep it
"up".
arf
arf@gagme.chi.il.us (jack schmidling) (03/15/91)
Article 4097 (15 more) in sci.bio: From: kuento@kuhub.cc.ukans.edu Subject: Re: moth flutter >Moths and many other insects are attracted to bright lights because they try to keep the light *above* them as they fly (this is normally where the moon will be in their fiel it is programmed to consider "up". > If you ever look closely at a moth circling, you'll notice that the moth is tilted strongly sideways, perpendicular to the long axis of the light source. ARF says: Perhaps the key lies in the above but I fail to see it. Try explaining it using flourescent tubes in various attitudes and then with a point source. I have visions of a moth flying on its side, endlessly circling but never having to get near the light to keep it "up". arf