Re: anti-borer tactics
On Mon, 20 May 1996, Nell Lancaster wrote:
> But there are really two questions here: What does the iris borer moth eat?
> and How does it recognize iris in order to lay its eggs?
> If I could tell exactly when the moth emerges and how long it's active, I'd go
> for the floating row cover approach suggested earlier on the list (sorry, can't
> find message to acknowledge author). It's not beautiful, but it works with
> other crops and is non-chemical. My 'decoy' planting idea might really have
> some effect in combination with row covers over the 'real' irises. Row covers
> are only practical for those of us with small iris plantings, but they'd make
> sense for bigger growers to use selectively with specific clumps of pricey new
I have been following this discussion a bit and I finally got out all my
"pest" books to see if I could find any further info--An old one
identifies the Iris borer as Macronoctua onusta, part of the Noctuidae
family. The moths have "dark purplish fore wings and yellow-brown hind
wings. They appear from late August into October, flying only at night.
The eggs are flattened elaborately sculptured, first creamy white with a
green tinge, later lavendar."
I couldn't find this specific moth in my butterfly and moth guide, but
the Noctuid moths usually are nocturnal and feed on flower nectar--can be
attracted to light and sugar baits.
Yet another source says to transplant infested rhizomes in August because the
larvae leave at that time to pupate in the soil--and you can remove the
pupae by sifting the soil.
Hope this helps advance your efforts, Nell, and I will keep my eyes open
for more info on the moth's habits in other sources.
Williamsburg, VA Zone 7/8