The Bug Geek

There is something about my wife and wasps. I don’t know what it is, but she sees them, appreciates them, and finds them in bizarre places more than any bug geek I know.   I usually overlook then, tending to favour critters with elytra…but there she’ll be, carefully bagging a handsome Ichneumonid to add to her collection.   And this is something she does for FUN, not because she’s a student of entomology.  Just because she likes them *SWOON*.

This VERY rainy day had me down in the dumps…after so much nice weather it seemed a shame to waste even a single day with non-stop deluges.  Plus, I kind of felt like I got my photog mojo back this week, but clearly I was not destined to spend time outdoors today.  I was cleaning the litter boxes in the laundry room and pouting.   My wife was starting a fire in the wood stove.  There was a rap at the laundry room door, and her voice: “I have something to show you…”

She held out a small log once destined for the fireplace, but her keen eyes had picked up something better than simple fuel for the stove:  BUGS!  I was not surprised to see that she was presenting something wasp-ey:

Mud nest

Two of these small round mud structures, plus a third that had been broken off at some point, formed a neat line on the bark.  She had *swoon* carefully picked an intact one open to see what was inside.  It was this:

Inside the nest.

Now this is really, really cool.  The plump, buttery larva is immediately apparent, of course, but there are other nifty details here.  Note the pale, shiny membrane lining the inside of the structure (on the left of the larva): a silken cocoon that likely repels both water and bacteria.  Small, brown, roundish bits to the left of the critter are likely the frass remains of its last meal.  Behind the frass, a hairy-looking greenish mass, better seen from the other side:

View from the rear

which really looks to me like exuviae (shed skin)…it could alternately be the remains of this larva’s victim (more on that in a moment).  You can also see a nice wad of pale silken strands on the left.

These lovely nests were built by a female potter wasp (Eumeninae, possibly Eumenes sp.).  The round shape and fluted “doorway” are characteristic of the subfamily; it’s said that, historically, humans modeled their own artwork after these beautiful structures.   The nest’s doorway is dead centre in the first image; you can see a seam on the right-hand side of it that represents the backfill placed by the wasp after she deposited her egg inside.  

Although adult potter wasps eat flower nectar, the larvae are carnivorous.  Females first construct mud nests for their offspring, then capture larvae (typically beetles) and place one inside each nest.  An egg is laid within.  When it hatches, the neonate wasp eats the captive beetle larva.  The “exuvia” in the images above could be all that’s left of the wasp’s meal, but it’s hard to say without picking it apart under a microscope (which I do not have at my disposal here at my desk, sadly). 

Click here for some pretty pictures of the very attractive adult wasps.