Last week Julia and I conducted a survey for leaf-mining moths at Black Rock Forest in New York’s Hudson Highlands region. I think we identified around 70 species, but as is often the case with fieldwork, some of our most interesting sightings had nothing to do with what we were looking for. At one point, for instance, Julia said “something weird is happening…” or something along those lines, which prompted me to look up and see a large object buzzing past. I chased after it until it landed on a witch hazel overhead, and only then was I able to confirm my impression that it was a bald-faced hornet (Vespidae: Dolichovespula maculata) carrying some other kind of yellowjacket (Vespula sp.).
I include the grainy photo above only because it shows the yellowjacket while it was still intact; the hornet now proceeded to crunch audibly on the smaller wasp, yellow and black chitinous crumbs raining down, all the while hanging by a single rear leg. By holding my camera with my arms stretched overhead and squinting through the viewfinder, I was able to get some closer shots of this process.
After three minutes of constant chewing, it was down to just a portion of the thorax. This was the last photo I took, and we went our separate ways soon afterward.
BugTracks 
Amazing photos.
I once sat and watched bald-faces snag horse flies from a roof. It made me a fan. If they will eat dreaded yellow-jackets, even better!
Other than the obvious size difference, and similar nutritional content, I wonder why the Bald -face selected this particular food source? They are known to be carnivorous, but since they are technically a yellow -jacket and not a hornet, that seems awfully close to home!
Could just be random/opportunistic, but it might also be removing competition–it reminded me of coyotes killing foxes, and wolves killing coyotes. (Actually, the one time I personally witnessed this–via tracks in the snow–some coyotes killed a gray fox and just left it there without eating it; it was scavenged the next day by a red fox and a fisher.)
I agree that it is probably territorial protection of any perceived competitor. Evolution produces survivors.
Some species of organisms show cannibalistic behaviour and even eat siblings or their own young, so this is not surprising.
OK. I’m wowed! Really interesting to see this behavior down to almost the last nibble.
I recently watched a very similar event in South Carolina, although I don’t know the names of the species I saw. It was horrifying and fascinating at the same time. My photos aren’t as clear as yours, but I do like to record the things I see, if only for my own reference. I had never witnessed anything like this before, so I’m glad to learn from your experience and images. Thanks!!
Absolutely fascinating!!
It was our pleasure to host you and Julia here at Black Rock Forest, Charlie. Very glad that you got 70 species of leaf miner in a short trip! It was very nice to see your blog, and I’ve never seen a yellow-jacket disappear before, especially in such detail! Bill Schuster
I shared your column with a local Maritimes insect group, https://www.facebook.com/groups/123663394923723/?ref=group_header, and I know you got at least one new follower.
Cool!
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Interesting that the bald-faced hornet ate the yellow jacket from tail to head.
Birds eat fish, head to tail. Foxes/cats eat their prey head to tail. Snakes eat frogs/toads head to tail.
Well, the tail end is certainly the end to be worried about on a yellowjacket! I don’t think there are hard and fast rules for these things, though. I can remember on two occasions seeing the front end of a frog sticking out of a snake’s mouth, for instance.
Some time ago I found a source saying that bfh feed on other yellowjacket species, and it took me a long time to find anything that backed up the assertion. I came upon a paper written in the first half of the 20th century (I’d provide details but I moved desks recently and the paper is in the unsorted pile) that documented this predation. It even went so far as to say that some bfh nests have a yellow hue from chewed up yellowjackets being incorporated into the nest envelope. I’d like to see THAT corroborated. Thanks for another great observation Charley!
Whoa, I’d like to see that too!