28 February 2016

The Anatomy of Caterpillars

Moth Caterpillar. Possibly Angle Shade

If Insects Were People

As promised this week's post has a more scientific vibe than of late.

I came nose to nose with this caterpillar the other day. I know we have to love all god's creatures, but I found this guy rather unnerving. He's too green, too juicy, too ... erm ... priapic, shall we say.  Quite a challenge for an old maid like me.

However, we shall be sensible, shake such thoughts from our minds, and carry on with our entomology lesson.

Focussing on the head first we can observe two lines of dots. These are primitive eyes, called ocelli. They can only detect changes in light. And aren't leering at me at all.

Caterpillar anatomy: ocelli and antenna

If we zoom in we can also see stumpy antennae, and vicious little mandibles.

Of course, we know all anatomical parts get turned to soup and are reformed in the pupal stage. The eyes somehow become complex compound eyes, and the antennae elongate out into elegant feathery eyebrows. 

The delicate angular legs of the final moth or butterfly develop from the caterpillar's first three pairs of legs.  

caterpillar anatomy: thoracic legs and prolegs

You can see them here on our voluptuous friend. This area will turn into the thorax. The stumpy hind legs, called prolegs, get absorbed into the abdomen.

I think this caterpillar will turn into an Angle Shade moth (or something similar), a more attractive, yet still unsettling creature.

Source RHS



Poor chap, I shouldn't be so disrespectful.

As adults we are discouraged from attaching human characteristics to animals. It's not only sentimental and unscientific, but ethically dubious, in that it assumes the human way is the superior way of being.  Conservationists and environmental campaigners make an effort to talk about nature with cool dispassionate facts.

However, in a great little film called Greenbees Greenpeace has embraced anthromorphism, with animated bees acting like eco-warriors, valiantly fighting to save us humans from poisoning ourselves with pesticides.

I think it's good fun, and a nice example of what I was talking about with the recent post Two Films: One Problem.  It even has echoes of Julia Roberts' 'I don't need you. You need me' message.

There is a growing understanding amongst environmental groups that constant doom-laden news has a demotivating effect. A sense of helplessness can set in. Forces of destruction seem too big for one person to change. To counter this tendency organisations are now using emotion and humour to create a feeling of hope and enthusiasm.

The Greenbees film is part of The Bees In Decline campaign on the SOS-Bees site. It is comprehensive, worrying, and very very professional.