Wednesday, July 11, 2012

Dancing Caterpillars

Saddleback caterpillar- Patrick Coin
A soft and juicy caterpillar is a delicacy enjoyed by some other insects and many birds.  Some have evolved defensive measures such as stinging hairs to deter predators.  These can cause a burning sensation on the skin if you touch them, especially when the skin is thin.  The Saddleback caterpillar is an excellent example.  The coloration which attracts us serves as a deterrent to many predators, saying "touch at your own risk."

Black Swallowtail osmeteria-

Swallowtail caterpillars can raise a stink with glands called osmeteria.  These are located on the head and only appear when they are disturbed.  They fill up like a circus balloon and leave a faint bad odor when smelled up close.  Touching the back of one of these caterpillars can cause it to rear back with its osmeteria distended, trying to reach you.  No threat to a human but effective if you are small and close up.

A major threat to caterpillars, or cats as we Butterfly House wranglers refer to them, are parasitic wasps.  Many tiny wasps lay their eggs on caterpillars.  Their larvae then enter the cats, changing their metabolism or even their behavior.  After developing inside the cat, they emerge and the wounded cat fails to pupate.

Some caterpillars rare back and toss their heads around when touched, attempting to drive off the predator.  Gregarious caterpillars such as those in the video below feed in clusters on the same plant.  They may use this head tossing as a group defensive maneuver.   In Dr. Chris Barnhart's words:
"Gregarious caterpillars may get some defense from parasitoid wasps by flinging their heads around when disturbed. The parasitoids have to get close to lay their eggs and can be knocked away. Being surrounded by others, all flinching at once, probably makes this a more effective defense."
Roy Thompson of our Butterfly House wranglers has recently advanced the science when he noticed that Mourning Cloak caterpillars would also toss their heads around to sudden sound.  He has now connected with them through music- he has them responding to rap! Watch their heads carefully as they dance to Roy's Cat Rap below.

Music and vocal by Roy Thompson
Filmed and directed by Dr. Chris Barnhart
Produced and edited by


  1. Don't think they will make the top 100 hits...but maybe...if the choreographer gets rhythm:)

  2. Do you know of any other caterpillars that do this? I have dancing cats on my curly willow; they have 10 yellow spots on each side, the rest of the body is black. The Mourning Cloak cat pictures I have seen show orange spots.
    Jae Hallbick
    Butterfly Nanny, Botanical Gardens of the Ozarks