Friday, December 13, 2019

Everything you wanted to know about the yucca moth, but were afraid to ask...

How does the saying go? The more you know, the more you realize you don't know? Something like that. Anyway, I knew yuccas were pollinated by a moth, but there was so much more I didn't know about the moth and it's relationship to the plant.

This pod is one I picked up on our travels in Arizona or New Mexico, years ago. I've always suspected we didn't have the yucca moth up here in Portland, because I've never seen a seed pod on our yuccas. After listening to the In Defense of Plants podcast called The Sex Lives of Yuccas I emailed their guest from that show, Syracuse University's Dr. Kari Segraves, and asked her. She grew up in Eastern Washington so I figured she would have some familiarity with our yuccas. Her reply: "You won’t see any yucca fruit in the PNW because the moths don’t get that far west. It’s probably because the native yuccas (Yucca glauca) don’t extend beyond central-western Montana. What I think happens is that essentially, the planted yuccas aren’t common enough to support the pollinators. I also don’t find bogus yucca moths in that area either." Wondering what a bogus yucca moth is? Listen to the podcast to find out.

See that small hole? Moth larvae on their way out...

Here's one of the few remaining seeds from the pod, it's been snacked on by the moth larvae.

There's another hole at the top right in this photo. Thanks to the podcast I know if the yucca moth gets carried away laying eggs the yucca can abort the flowers (not allowing them to mature) and thus the moth larvae never get the chance to develop. It's an complex relationship. Go listen to the podcast, really...it's very interesting!

Weather Diary, Dec 12: Hi 54 Low 45/ Precip .31

All material © 2009-2019 by Loree Bohl for danger garden. Unauthorized reproduction prohibited and just plain rude.

10 comments:

  1. So glad to see you promoting that episode- it blew my mind and left me giddy. Especially the thing about the plant and moth more or less "agreeing" to an acceptable amount of eggs laid, and it being something wildly specific, like 11 eggs!
    In the heart of the western yucca distribution and common landscape use, we are always perplexed by which species in our gardens do and don't get pollinated, and when they do, they are sometimes hybrids with other nearby species. For instance, I am making conscious efforts to plant groups of Yucca rupicola (from TX) in my Landscapes in hopes that they will get pollinated so we have a domestic/garden seed source of this fantastically green thing, because the few numbers that are in gardens seem resistant to set seed. They may bloom at the wrong time for the local moth or have the wrong floral structure...

    I have also tried several times to artificially pollinate plants; it must be trickier than I am, because it has not truly worked. I know it is possible, having read about someone in Holland (no yucca moth there!) crossing yuccas.

    Fun stuff! Thanks for posting this!

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    1. Ah, good to know I"m not the only one who listened and loved it...and ya....I was going to include that there was a specific number but I couldn't remember how many and didn't have time to relisten. I do hope people click and listen for themselves because it's so good! I too thought about trying to pollinate a few of mine by hand, just because I love the pods!

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  2. Thanks so much for passing on this information, I had never heard of the Yucca moth and had no idea how they were pollinated. The relationship between plants and insects is so intricate, fascinating, and delicately balanced.

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    1. Indeed it is! I hope you have time to listen to the podcast, it's really fabulous.

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  3. I'm pretty sure that Yucca filamentosa is what is common around here, and I get loads of seeds every year, with no visible damage. Are all yucca species pollinated by moths? Do you want any seed?

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    1. Ya they're what's common here too, but not wild occurring. Yes, all are pollinated by moth, except for a few in Holland evidently (see comment from Kenton above). Thanks for the offer of seed, but no thanks. I don't need any more plants... I just want to see the pods develop on my blooms!

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  4. I can't say I've ever seen a yucca moth here either although bees routinely swarm our common Yucca elephantipes. However, when that monster plant occupied our own back slope I never saw any signs of seeds. Despite the fact that the plant (or rather yucca forest) was dug out years ago, pups are still popping up.

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    1. Hmmm...now you've got me trying to remember if I've ever seen a seed pod in SoCal...

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  5. I've listened to the podcast and was owe struck (again) by the relationships that develop in nature, most of which we know nothing about. Hooray for scientist who study this and are able to shed a little light on the goings on that are always evolving. I will be looking at my own Yuca with fresh eyes, that's for sure.

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    1. Glad you gave it a listen, pretty fascinating stuff!

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