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Sunday, September 23, 2007

Hunter as hunted

I watched part of a neat little drama in my Longmont, Colorado back yard yesterday. While I didn't see the opening act, my attention was drawn to movement on a flagstone pathway underfoot. Stooping over, I saw a small black wasp dragging a spider along backwards. I spooked the wasp and it flew away, but when I backed off it returned to claim its trophy and continue to drag it along the pathway.

I ran inside to get my camera, and by the time I got back outdoors it took me a while to re-find the wasp & hapless spider- the wasp was making quick progress. It was hard to snap pics because it moved so fast, and when I got in too close the wasp would drop the spider and run or fly off. Luckily, it kept coming back to its victem, and eventually it dragged it up and over a low retaining wall.

It left the spider along the wall and began enlarging a burrow in the sandy substrate under my flagstone patio. I had noticed these burrows and sandy spoil piles near my grill but didn't know what was doing the digging. Well, now I know. I looked into the situation and I think I found an apt description of these wasps here:
Belonging to the family Pompilidae, these spider-hunting wasps immobilize their prey with a sting, drag them to their burrow, and lay an egg in the spider. The hatched larva consumes the spider and then pupates in a protective cocoon to wait out the winter. Vicious world, isn't it?

If anyone knows more about these wasps (in general, or this specific one) I'd love to hear from you.

I also made a little video that shows the digging behavior and the spider transport & burial. Somehow I decided to add a little soundtrack and narrative, too- procrastinating more serious work, I guess. Enjoy-


Michael H. said...

Nice little video clip. Don't dismiss the possibility that it's of the genus Chalybion, or of the family Sphecidae. The image looks a lot like Chalybion zimmermani which I observed in Indiana back in the 70's (though they burrowed into rotting wood). Don't know what you have in CO. Check out

Patrick B. said...

Too cool. I can't believe how fast they dig. It reminds me of the Thread-waisted Wasps here in NJ. They usually stuff the hole with a big, juicy caterpillar though.

Anonymous said...

Love the soundtrack and the commentary. It's amazing how much occurs all around us that we would miss if we weren't paying attention.

katiebug123456 said...

All cool. that was so cool you sod see me bab.

Anonymous said...


Down here in the Pueblo area we have tarantula hawks, large black wasps with wonderful orange wings. Found some pix and a movie like yours at

and another photo at

They are really gorgeous but I understand they pack a pretty mean sting. I've also seen other predatory wasps carrying caterpillars and stuffing them into holes in the ground, but I have never seen one actually digging the hole like yours.

Margie Joy, Pueblo West