My New Book


Caterpillar Fierceness

black swallowtail caterpillars

If you watched the caterpillar shed video in the earlier post, here is a little background info. As caterpillars grow, they shed their skins. The period between each shed is called an instar. Monarchs do this too as they grow, but what’s fun about black swallowtail caterpillars is that they change color. When tiny, they start off resembling bird poo and not a protein powered snack a bird might want to eat and as they get larger, the coloration switches to help them blend in with parsley stalks. The caterpillar that shed was in its third instar and then shed into the fourth looking completely different. Pretty cool huh? Here is a cool site that helps explain it.

One of the cool things about black swallowtail caterpillars that I neglected to mention during last year’s ranching season was their crazy defense mechanism. When threatened, two little orange protuberances that resemble horns pop out. Note the horns on the above black swallowtail caterpillar? They have a strange aroma and they whip their heads around flashing their horns. I think the smell is supposed to repel potential predators, but in my case, it just fascinated me.

They even have them when they are tiny caterpillars. Beware the mighty black swallowtail caterpillar! And of course, I corralled Non Birding Bill into helping me video it. I’ve read that you can squeeze your swallowtail cats to get them do this, but I don’t recommend it–why risk the injury. Sometimes just brushing parsley near their butts results in the stink horns coming out. In the video, NBB is just barely grazing the cat with a Q-tip. Here is the video:

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4 comments to Caterpillar Fierceness

  • momo

    It’a a caterpillar rodeo!

  • Beverly

    I read somewhere that that’s how they catch those caterpillars. Any critter who can produce horns surely does when wrangled, but unfortunately in the case of Black Swallowtail Caterpillars, it is more of a hindrance than not. Once they are mad enough, the folks who want to catch ‘em toss a lasso of hemp string right around those horns and drag the fierce, struggling, horned monster into captivity and keep them in thick-walled plexiglass cages like you have there.

    PETA is working up a campaign to stop such treatment of BS caterpillars…they plan to splash International Yellow paint on the hands of all involved.

    Be careful…be very careful!

  • Crystal

    Now that there is one terrifying caterpillar. I’d be in fear for my Q-tip.

  • Susan Gets Native

    We recently found zillions of these guys in the yard (here’s to NOT mowing every single Queen Anne’s Lace down!) and when Isabelle picked one up, it did its osmeterium thing, I first thought that she had squeezed it too hard!