Speyeria cybele: Defending nectar

bill and Dale droberts03 at snet.net
Tue Jul 17 12:53:40 EDT 2001


Everybody,
I'm curious if anyone else has observed anything like what I'm going to
describe?  My Buddleia davidi (Butterfly bush) is approaching tree-like
dimensions this year and as a result attracts numbers of Speyeria cybele
(Great Spangled Fritillary) and others from my nearby fields.  Normally
all is a "peaceable kingdom" on the blossoms as the various individuals
and individuals of different species politely drink their fill, making
room for others and occasionally exchanging places.  When a Monarch
entered the Buddleia air space a couple of days ago peace ended. Almost
immediately a Great Spangled Fritillary (GSF) engaged the Monarch in a
spiral air battle. It was the kind of ascending circling and jockeying
for position that you would normally associate with two members of the
same species inspecting each other for sexual prospects.  However this
seemed to be a case of the GSF trying to drive the Monarch away from the
nectar source.  About 20 feet away from the Buddleia is a patch of
Common Milkweed (Asclepias syriaca) which the Monarch tried to approach
a half dozen times but was driven off each time by a GSF. This
interaction went on for a least an hour, maybe longer, as I drifted off
to other things. I'm not sure it was the same individual GSF that
engaged the Monarch each time. It very well could have been different
individuals  harassing the Monarch because there are generally five or
more GSF at my gardens at any one time this part of the season. Then
again it could have been the same GSF that had it in for this Monarch.
    So I guess my question for the group is this:  Does this behavior
suggest a case of mistaken identity (GSF mistakes Monarch for another
GSF and possible mate or rival) or does this suggest GSF's (or an
individual) defending a nectar source? I'd be interested in any
comments.
                                                                 Thanks
all,

Bill Yule


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