giant swallowtail returns

[Chris Conlan]

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>Would larvae reared on it go looking for it when they got around to
>laying eggs?
 
I don't know of any studies exploring this question but I really doubt it's
the sort of thing that happens overnight.  In other words, I find it rather
unlikely that a single instance of a butterfly laying on a substitute host
will create a whole generation of butterflies that are all out searching for
the substitute.  In most cases I really think this is something that takes
time.  In the instances which can be cited where a butterfly jumped on to an
introduced host right off the bat it would likely be found that there was
little difference between the substitute and native host in the chemical
cues being used by the ovipositing female.  It might even be that in some
cases the substitute may be even more attractive to the female.
Another thing worth noting is that I think we give the butterflies too much
credit in botany class!  They are good but I have seen them lay on the wrong
(and unacceptable) host many times.  Plenty of times I have found buckmoth
egg rings layed on the wrong plant or gulf frittilary eggs on the side of my
house several feet from the nearest passion vine.  However, one has to
wonder if there isn't some sort of purpose to this.  Seems like the little
caterpillars manage to find their way back to the hostplant much of the
time.  Maybe (here goes more speculation) by laying on the wrong host, but
still within walking distance of an acceptable host, parasites or predators
are less likely to find the eggs?  Anyway, just something I've pondered from
time to time.
 
Chris