Hey, Colibri, come talk to me about fuzzy French caterpillars!

Sunday afternoon Bonzo, the Better Half, and I sat on the couch and watched this movie, on a tape from the library.


What I want to know is, what kind of caterpillars were these? It was difficult to tell the scale, but they looked about 4 inches long, as big around as my thumb, very fuzzy, and with brown, black and white rings. The thing is, they were marching all lined up, with head firmly stuck up the guy in front’s butt. There was this single file caterpillar parade, with what looked like hundreds of caterpillars, and at one point, the filmmakers showed two lines converging, and it was like a highway on-ramp. Eventually the second line simply budged into the original line, leaving the budge-ees from the original line standing there in puzzlement, now on their own on-ramp. Then they showed them all going around in a big circle, and then they showed them in a big pileup.

Okay. So I said, “That’s not natural behavior. The filmmakers have set that up somehow, picked up caterpillars and moved them around to make it look like a highway on-ramp, and to get them moving in a big circle, and especially the pile-up. Fun’s fun, guys, but come clean.”

And Bonzo and the Better Half said, “No, it’s like with bagworms, they get in a big pile like that for mating.”

I said, “Yes, but bagworms are up in a tree, in a bag, for safety. These guys are just right out there on the bare ground, buffet froid for any bird that happens to see them. And how could marching in huge lines right out in plain sight like that have any survival value? If they’re going to pack up and move to a new food source like that, en masse, I would think it would be safer to do it at night.”

So? You’re the Bug Man. What are these? And was it all staged? And [shudder] do we have them in the U.S.?

The movie was filmed in France, and I saw references in the acknowledgements to the “Pyrenees du Midi” and “Jura”, if that helps, geographically.

And for some reason, checking Google for “marching caterpillars France” only brings up World War I websites.

Hi Goose,

As I am just on my way to lunch, I will try to answer this later after checking a couple of things. I saw Microcosmos when it first came out - it’s a wonderful film.

Processionary catterpilars are cool


Thank you Gaspode, for saving me the trouble. I think that the sites linked to by our friendly antipodean talking canine should answer all the questions posed by Duck Duck Goose. I would probably buy the explanation that they march together because they are distasteful, rather than that they are trying to resemble a poisonous snake.

I suspect the film-makers did some set-up of the scenes you mention, but the behavior itself is normal. If the caterpillars accidently get into a circle, I believe they may follow one another until they die of starvation.

Um, Goose, not to cast aspersions on the intelligence of your nearest-and-dearest, but in the caterpillar-sex column I said that caterpillars don’t mate with each other. In the bagworm, the adult male is a normal moth, but mates with a “larvoid” caterpillar-like female. As Cecil quoted in the column, “we can’t offer two caterpillars going at it” (much less an orgy).

Actually, I’m a Bird Man. Creepy-crawlies are just a hobby. But thanks for calling on me anyway! Anytime.

Okay, well, the Received Wisdom both in the Middle School Lunchroom and down at the Post Office (two remarkably similar environments, come to think of it :smiley: ) is that that’s what bagworms are doing in there, having sex, and that the bag functions as a sort of medieval bed hanging, so the lords and ladies can frolic at will, undisturbed by the gaze of lesser mortals.

Anyway, thanks for the links, Gaspode–once I heard the secret word “processionary”, my subconscious went, “Oh, yeah…” and a little light bulb went off. But I’d never actually SEEN them doing it. [shudder] Come to think of it, if I were a bird, I probably wouldn’t try to eat something out of the middle of one of those weird undulating fuzzy lines, either.