Iris Borer Moth

Subject: Iris Borer Moth
Location: Faribault County, Minnesota
September 24, 2016 4:09 pm
Greetings, Daniel!
I mentioned an Iris Borer Moth I saw years ago. Back in 2013 I still had Flag Iris growing in my Rain Garden. As I weeded, I found rotting rhizomes, large larva and numerous pupae, all of which got tossed into the yard for later raking up and taking to compost. The robins were quite happy with the feasts they found in the “weeds” I was pulling up! I even got a couple photos of robins with the grubs in their beaks!
Well, that summer I decided no more iris for me in my garden. Just before that decision, I was working in a section when I saw this large moth. It was resting at the base of an iris plant so I had my suspicions as to what it was. An absolutely gorgeous moth as I previously mentioned, with patterns reminiscent of Native American Cave Paintings or even petroglyphs. Being me, I took several photos from a couple angles to use for possible identification (this was before I discovered your awesome website!). And of course my suspicions were confirmed.
So here are three of my best photos of an Iris Borer Moth, taken September 2013. Enjoy!
Signature: Wanda J. Kothlow

Iris Borer Moth
Iris Borer Moth

Dear Wanda,
Your excellent images of an Iris Borer Moth,
Macronoctua onusta, are a noteworthy addition to our archives as this represents a new species for our site.  According to BugGuide:  “larvae bore into iris plants and feed on the rhizomes”

Iris Borer Moth
Iris Borer Moth

Wow, a new species for your archives! That’s fabulous!
This gorgeous moth I photographed was holding on to the base of an upright iris leaf so the moth was facing up (the pictures should be vertical rather than horizontal). I remember when I took the photo wondering how many people even get to see an adult Iris Borer Moth. People who want to grow iris are going to remove the larvae before they get to the pupae stage whenever possible, so the number of adults is not likely to be substantial. Then again, adult females can lay hundreds of eggs which keeps the population going …
I’m glad I could help your archives grow, Daniel.

Thanks Wanda,
We rotated the images because all images on our site are horizontal, and to orient them vertically, we would have had to reduce the magnification.

Gotcha …

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