Iris Borer Moth (Macronoctua onusta)

Order: Lepidoptera (le-pid-OP-ter-a) (Info)
Family: Noctuidae (nok-TOO-ih-dee) (Info)
Genus: Macronoctua
Species: onusta


This bug has been reportedly found in the following regions:

Macy, Indiana
Anamosa, Iowa
Lawler, Iowa
Belleville, Michigan
Minnetonka, Minnesota
Spicer, Minnesota
Montclair, New Jersey
Verona, New Jersey
Himrod, New York
Columbus, Ohio
West Chester, Pennsylvania
New Berlin, Wisconsin
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Members' Notes:


On Oct 3, 2012, themikesmom from Concord, NC wrote:

I've never had iris borers thank goodness..and would imagine they would thrive in the Southeast as it doesnt get the snow and constant below freezing winter temperatures. So if you are in zone 7 or above i would imagine they would be tough to eradicate in constant humidity. Although ive never had borers, I have had leaf spot and that is even harder to get rid of without the use of toxic fungacides that id prefer to never use. I would imagine as long as your bulbs dont get 'wet feet' and are in well aeriated non-soggy soil, than borers would not invade such plants, unless they are damp, weakened or diseased plants, which are much more succeptable.


On Jun 16, 2010, Conquered_MS from Preston, MD wrote:

Knock on wood, we don't seem to have a problem with this pest, but now that we have more than 250 irises, I fear the scent may attract them from somewhere else. Thus we operate a bug zapper light near our iris patch, to hopefully zap any that may decide to investigate our patch before they can do any damage. Has anyone tried a bug zapper for iris borer moths, and did it help?

Also, does anyone have a link to information on the life cycle of the iris borer?


On Aug 1, 2009, momstherapy from Lawler, IA wrote:

This pest totally wiped out my iris. Tried (and failed) spraying in the spring, pinching the larva while in the leaf and digging up and throwing away infected rhizomes. My only advice is: really examine plants/rhizomes you get from friends. Sometimes you get more than just the plants.


On Oct 25, 2008, EROCTUSE2 from Belleville, MI (Zone 5b) wrote:

Here's a more recent link to a better image of the adult moth.


On Mar 5, 2008, TBGDN from (Zone 5a) wrote:

My comments are too numerous to write here about this scourge of iris gardens in the eastern U. S. Over the past two years I've seen several questions posted in the Iris Forum about the iris borer and my hope is this comment will assist others with their questions. Instead of listing all my experiences with this pest, I'll insert a link to my journal where I've written a lot about it with several pictures. Here is that link: [[email protected]]

The only photo I don't have in my journal is the actual adult moth, so I'm inserting a link here for a great photo page by the Mississippi Entomological Museum at Mississippi State University. It is Item #9452 on that page. Here is the l... read more