Fall Cleaning

The November before last I posted a picture of some wasp larvae a friend had found in the burrow of a wood-boring beetle larva while whittling by a campfire.  The following May, I posted photos of the adult pteromalids.  I suppose it was in the name of keeping things simple that I neglected to mention the beetle larva that was still living in the piece of wood.

On November 22, 2011, the same day I took the picture of the wasp larvae, I took this photo of a beetle larva’s face peeking out of a hole (about 1.5 mm wide) in the same piece of wood.  If you look closely, you can see the grooves its mouthparts have etched in the floor of the tunnel.

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For context, here is a photo I just took showing the above burrow at left and the cavity with the wasp larvae at right.  I suppose I could whittle away the surface to see if they are connected, but it seems reasonable to suppose that this beetle species is the host for these wasps.

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On May 15, 2012, the same day I took those photos of the adult wasps, the beetle larva had popped out of its burrow:

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I tried to tuck it back into a hole in the wood, and it seemed to resume feeding:

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The day I took those photos, I left for a week on Nantucket.  When I came home on May 22, I saw that more wasps had emerged and that the larva had fallen out of the wood again but was still alive.  Two days later I took this photo:

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There is no note in my journal about this, but evidently I tried tucking the larva into the cavity where the wasp larvae had been, and then another adult wasp appeared from deep in the tunnel.  On May 25 I wrote, “it appears that yesterday I successfully re-implanted the beetle larva in the red maple chunk, after more days of writhing on the bottom [of the container].”  I checked the container throughout the year, and I’m sure I checked it this spring, but I don’t know exactly when was the last time I looked.

This week I’ve been going through all my vials, jars, and other containers, putting many in the fridge to overwinter and tossing some out.  When I came to the container with this chunk of red maple, I found the 4-mm adult beetle inside, unfortunately deceased:

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Since I had posted photos of the larva on BugGuide and had gotten feedback that it looked like a bostrichid (horned powder-post beetle) or possibly an anobiid (death-watch beetle), I browsed through the superfamily Bostrichoidea (in the process learning that things have been reshuffled and now Anobiidae is a subfamily of Ptinidae, which includes the spider beetles), and I believe it is the death-watch beetle Ptilinus ruficornis.  To really appreciate those antennae, you need to see a live one, and Joyce Gross has been kind enough to let me use her photo here:

Joyce Gross Ptilinus ruficornis

About Charley Eiseman

I am a freelance naturalist, endlessly fascinated by the interconnections of all the living and nonliving things around me. I am the lead author of Tracks & Sign of Insects and Other Invertebrates (Stackpole Books, 2010), and continue to collect photographs and information on this subject. These days I am especially drawn to galls, leaf mines, and other plant-insect interactions.
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2 Responses to Fall Cleaning

  1. Pingback: More Firewood Dwellers | BugTracks

  2. Joyce Gross says:

    Nice story and larvae photos. I love the never-ending source of interesting surprises when you pay attention to the little things.

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