Overwintering Hawk Moths? Lights
Chris J. Durden
drdn at mail.utexas.edu
Sun Oct 1 22:41:30 EDT 2000
>Date: Sun, 01 Oct 2000 21:40:10 -0500
>To: ecosys at pacbell.net
>From: "Chris J. Durden" <drdn at mail.utexas.edu>
>Subject: Re: Overwintering Hawk Moths? Lights
>In-Reply-To: <39D8292F.C8AFF5CB at pacbell.net>
>From 1968 through 1978 I had rewarding and often bumper mothing years at
two suburban locations in Austin, Texas. Not only were moths and other
nocturnal insects attracted to ordinary outdoor lighting, but blacklighting
was very rewarding. I have never had a good moth year in this suburban
setting in the 21 years since!
> What happened at that time? One corellative was the mass marketing of
"bug-zappers". These are left on most of the year. There is one visible in
almost every block. The drain on reproducing adult nocturnal insects must
have been profound.
> Do others have similar experience?
>At 11:20 1/10/00 -0700, you wrote:
>>"Martha V. Lutz & Charles T. Lutz" wrote:
>>> discussing this, a somewhat unpleasant hypothesis came to me . . . is it
>>> possible that this is an effect of light pollution?
>>> Presumably the Manduca larvae use daylength (shortening) as a cue to enter
>>> diapause (as a pupa, underground) rather than emerging as adults to start
>>> another generation. In the past few years I have found a very few newly
>>> emerged moths (of a variety of multivoltine species) late in the summer or
>>> early in the fall, and always assumed that it was simply genetic variation
>>> that could potentially allow expansion of the local population into
>>> Southern parts of the species range.
>>> Is it possible that these adults were, as larvae, exposed to outdoor
>>> lighting that artificially extended their 'days,' so that the daylength
>>> they perceived indicated that another generation would be successful,
>>> the real daylength was shorter and would have initiated diapause?
>>> >> In Stride,
>>> Martha Rosett Lutz
>Jeffrey Caldwell wrote -
>>I am glad to see you thought of that! I believe that light pollution is
>>enormous impacts that nobody even thinks about. I wonder how many people
>>"environmental impact statements" are taking it fully into account?
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