Re: Cult: Borers

I think Anner's post on the borer is right on the money.  The borer is a
native insect.  Since bearded irises were not found in North America before
European settlement, the original host must have been a native species.
The only native iris with significant populations in the present range of
the borer is Iris versicolor.  I think we can assume that Iris versicolor
was probably the original host, as well as perhaps more northerly
populations of Iris virginica.

Since the introduction of bearded irises in gardens, it is safe to assume
that the borer is on the move, expanding its range outward to any suitable
climate where irises are available.  The spread has been slow because the
dispersal abilities of the adult moths are weak.  But they can be carried
to new areas in infested rhizomes.

One thing that puzzles me about this scenario is that I. versicolor is
almost always found in very wet areas, or actually growing in water.  I've
found that while versicolor and virginica clumps growing in the border are
attacked, those in shallow water or boggy conditions are not.  I wonder if
the iris borer might not have been a very rare insect in the recent
past--or that it has another host plant, perhaps of a very different sort.

There were some earlier posts quoting old iris literature as saying that
borers attack other rhizomatous or tap-rooted perennials.  Though I've
never seen this personally, it could account for the borer's original
distribution (maybe Iris versicolor was not the main host, but an
occasional one) and the constant re-infection of iris gardens.  Anybody out
there ever found an iris borer in, for example, a columbine root?

In summary, it looks like there is a good deal of research yet to be done
on this insect.  AIS would do well to interest the Entomology Department of
some university Agriculture School.

Bill Shear
Department of Biology
Hampden-Sydney College
Hampden-Sydney VA 23943
(804)223-6172
FAX (804)223-6374
email<bills@hsc.edu>
Other Mailing lists | Author Index | Date Index | Subject Index | Thread Index