Ootheca

Praying mantis ootheca - bird predation

I don’t spend very much time looking at the exterior walls of the house, except for at one time of year: those first warm days of spring. Having noticed the small milkweed bugs gathered in the warm, sunny patches along the south wall of the house last Friday, I walked the length of the south and west sides looking for anything else that might have come out to enjoy the gorgeous afternoon.

Aside from a couple of small spiders and two lethargic flies, I didn’t find any other critters. I did, however, discover this. About an inch long, it was stuck very firmly to the concrete foundation on the west wall, not too far from the bird feeder Dan installed against the window. Leaning down to peer at it I could make a guess at what I thought it was, but after I peeled it from the wall and could look at it more closely I was certain. Can you guess?

Praying mantis ootheca - bird predation

It’s the paper shell of an ootheca, the egg case of a praying mantis. I’ve only ever seen these once before, nearly three years ago, back in Toronto. (It was in one of the earliest posts on this blog.) At that time I noted that they were generally found on the sunny south side of structures; this one was on the sunny west side. They superficially resemble cocoons at first glance, but they’re firm to the touch, whereas cocoons are generally springy. They’re also segmented, and this is visible even from the outside. The sides are ridged in narrow strips indicating the segments of the case. On the top the segments come together in a pattern that kind of resembles a zipper, creating a seam.

Praying mantis ootheca - bird predation

It’s hard to see that on this one, though, because it’s been torn apart. I suspect a chickadee, and not just because of the ootheca’s proximity to the bird feeders. Plastered a foot and a half up the wall as it was, it’s probably out of the reach of a small rodent (as well as ground-foraging birds like sparrows). I’m not sure whether a red squirrel could have reached it from the ground, either, but since it was on the concrete I at least know that the squirrel couldn’t have come across the wall to it (with our log house they have no trouble scampering up and down the exterior).

The only feeder birds that have feet strong enough to cling or hang from things are chickadees (goldfinches sometimes do too, but with much less frequency). I can just picture a chickadee clinging precariously from the ootheca, its tail fanned against the wall as it hammers on the hard shell of the case between its feet, digging out the protein-filled eggs inside. It also looks to be a pellet of dried bird poop sitting on the top of the case in the first photo, but I couldn’t rule out the possibility that this was from a feeder visitor and separate from the predation event.

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As an aside, I apologize for having fallen behind with comments; before the puppy came home I was busy trying to wrap up stuff to do with the moth guide so it’d be out of the way, and now that he’s here I spend most of the time that I’m not tailing after him just trying to be moderately productive. I really appreciate hearing from everyone, though! I’ll hopefully catch up soon.

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4 responses to “Ootheca

  1. what an interesting post. now i am curious to do more investigations into the topic. hope you and raven are enjoying your new puppy!

  2. Very cool that you can deduce the perpetrator–I mean predator! Enjoy your puppy!

  3. Thanks for your comments, everyone! And the pup’s doing great, growing and settling in really well. He’ll probably be showing up more regularly on the blog soon, with Raven on our hikes, now that he’s moving around a bit better.

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