My New Book


The Poop On Caterpillars Looking Like…Poop

Kinda sorta bird news here. Some readers may remember from the black swallowtail butterfly ranching that I did last summer that the caterpillars dramatically changed colors as they grew. When first hatched, the black swallowtail cats looked like little bits of finch poop–which I thought was incredibly interesting because unlike monarch caterpillar who stay on the underside of a milkweed leaf, swallowtails hang out on the top of a parsley plant–what a great disguise, who would want to eat something that looked like bird poop?

Well, according to National Geographic, new study by Japanese researchers shows that a single juvenile hormone is responsible for the changing of colors. The hormone levels drop when the caterpillar leaves the bird-droppings stage and begins its green color transformation.

Read the rest of the story here.

2 comments to The Poop On Caterpillars Looking Like…Poop

  • dguzman

    When I was little, we used to get these ‘pillars on our citrus trees–they really looked like poop: white and light brown, kinda oily-shiny-wet-looking. I know it’s not much of a description, but could you offer a guess? We just called them “doo-doo worms.”

  • TomStarling

    It is interesting that predators avoid the caterpillars because they resemble bird poop. Perhaps they think that bird droppings are harmful? To humans, bird droppings are potentially very harmful, as continuous exposure can lead to over 60 potentially deadly diseases. Perhaps nature knows that bird poop is not as innocent as it seems.