Beware of the Caterpillar!

Not too long ago, my boys along with some friends down the street, found a caterpillar in our yard.  It provided fun for everyone as they passed it around and all took turns holding it.  The above picture is the caterpillar crawling on our neighbor's shoe.  Why are we so fascinated with caterpillars?  Had this been a spider, we would not have been anywhere close to it!  I think knowing that one day it will be a beautiful butterfly makes caterpillars so likable.

I decided to do a little research on caterpillars to see if they really are as harmless as we tend to think.  For the most part, they are, but I did learn some interesting things.

Caterpillars are rich in protein making them food for many animals.  I think I'll get my protein from other means, though!  In order to protect themselves, they have evolved various means of defense.

• Some use their appearance to ward off predators.  Markings and certain body parts can make the caterpillar seem poisonous or bigger in size, making it more threatening and non-edible.

 Monarch Butterfly Caterpillar

photo courtesy of tulane.edu

• Some are actually poisonous and can shoot acid.
• Some have long "whip-like" organs that they can wiggle to frighten away flies.
• Some blend in by resembling the plants on which they feed by their color or by mimicking plant parts such as thorns.

Saddleback Caterpillar

photo courtesy of Gerald J. Lenhard; insectimages.org

• Some use a silk line to drop themselves off of branches when disturbed.
• Some have spiny bristles that can get lodged in the skin or mucous membranes.

Costa Rican Hairy Caterpillar

photo courtesy of David M. Jensen (Storkk); wikipedia.org

• Some have bristles associated with venom glands, called urticating hairs.  While most of these only produce mild irritation to dermatitis, this is not the case for the caterpillar of the South American silk moth.  Its venom is an anticoagulant that is powerful enough to cause a human to hemorrhage to death!  This venom is among the most potent defensive chemicals in any animal. 

South American Silk Moth Caterpillar

photo on www.cmaj.ca;  courtesy of Roberto Pinto Moraes (Butantan Institute)