Thursday, September 29, 2016

One Bug's Trash is Another Bug's Treasure

If you have ever heard of a green lacewing of the Chrysopidae family, you might know that its larva interestingly camouflages itself with lichen.  Every green lacewing larva I have seen has a dust lichen called Lepraria finkii adhered to its back.  It sticks the lichen to hair-like setae on its body so it can hide under a blanket of lichen. Perhaps to hide from prey that it can grab with its large mandibles.  This fall, try searching trees for these critters by walking up to the trunks and watching for little moving lichen balls.  If you touch the lichen ball, they will walk away from you.

This camouflaged lacewing larva shows mandibles sticking out on the left, legs out the bottom.  Lepraria finkii covering its back.
I have heard about a green lacewing larva that will pick up other kinds of debris and stick it to its back.  But I have never seen it before.  I've seen pictures of a lacewing larva carrying numerous land snail shells and insect body parts on its back.  It looked like a top-heavy garbage truck sneaking across the ground.

This fall, during one of our local school field classes, some 4th grade students and their teacher from West Union Elementary hit the jackpot.  The students were instructed to explore food chains within a leaf litter sample.  Each group sorted through the animals found in their leaf piles.  From this search, a little mysterious critter was found that appeared to be a moving heap of debris.  The teacher brought it to Robyn Wright-Strauss who was leading the class to identify the curious animal.  Robyn brought it back to the lab knowing this was a very unique find.  It was the debris carrying lacewing larva.

Lacewing larva carrying snail shells, insect parts and spider parts on it back.
This animal had collected pieces of other animals and stuck them to its back. I would assume the debris on the lacewing's back was found on the ground and not leftover pieces of its own prey.  Some of the exoskeleton pieces seems to be from an ants, possibly beetles, and there is a dorsal side of a cephalothorax from a spider attached as well.  Two Striatura snail shells are attached on top.  Since lacewing larva specialize in more soft bodied foods, I would think ants and spiders are not their first choices.  So it probably picks up any debris that's available, attaches it, and then blends in with whatever it has found for a disguise.    

The larger snail shell on its back is 2.5 mm and was very difficult to pull off.  Its adhesion is quite impressive.

A pile of debris makes a great place to hide.
What a nice find from our local schools.  Enjoy this short video of the lacewing larva. Now that you've seen it and know what to look for, maybe you will find one too.

Posted by: Mark Zloba