Dennis suggested that onemight apply pepper spray applied to irises at
the time borers
are laying eggs would cause them to seek out other places?
Unfortunately, the moths do not normally lay their eggs on the irises
but on the plant debris in the surounding area. Cleaning up the debit
each autumn and spring may reduce the population to the point that it is
no longer a nuisance.
Earlier discussion on iris-l has suggested that the natural host of the
borer is the versicolor-virginica group of native irises. They
certainly like versicolor in this area. Someome asked if the borer was
an introduced pest from Europe. The answer is no, the bearded iris
itself is the introduction and this might explain the problem.
Ian, in Ottawa where new irises are beginning to open each day, starting
with pumila, and then some dwarfs. I. burcharica and magnifica are