Tuesday, May 25, 2010

Case moth information

theregatha asked me about casemoths and I have found some information.

 I remember having a casemoth in my classroom many years ago.  It was kept in a fish tank but escaped!!  We had an unusual room which had extremely high ceilings that had large wooden beams across the room.  Every day we would wait till someone spotted the casemoth high above our heads and call out "There it is!".  I have no idea what it used to eat, there were definitely no plants up there.  It stayed for several weeks and we never did discover where it went.

Anyway, back to the point.
I have found information about casemoths at the Queensland Museum site.
Some of the interesting facts I found:
Case moths spend most of their lives as caterpillars, the larval stage, which may last for up to 1 or 2 years in some species.  Once constructed, the caterpillars never leave their cases.  The head and thorax of the caterpillars are quite heavily armoured and they have 3 strong pairs of legs on the thorax with which they move around, dragging the case behind them.
This is the one at our front door, showing its thorax and legs.

Here is a clue about what it eats, but not really what the one in our classroom found to survive on.
Many species of case moth caterpillars are plant feeders; others feed on lichens; while some live within the nests of ants and are thought to be scavengers.
I think my pictures are of a Saunder's Case Moth (Metura elongata).  According to the Queensland Museum site,
Its biology is typical of those species where the adult female is wingless. 
One of the amazing parts is how it attached the twigs to its case.
The caterpillar uses its jaws to harvest a twig of a desired length, attaching it to the mouth of the case with a few strands of silk.  The caterpillar now withdraws into the case and, from the inside, cuts a small slit in the bag.  This may take almost an hour to complete because the material of the bag is incredibly tough.  The caterpillar then sticks its head and thorax out through the hole, reaches up and grabs the twig and cuts it free.  Withdrawing back into the case, the caterpillar holds the base of the twig in the hole and sews it firmly into place with silk.  From start to finish, the process takes about one and a half hours to complete.
Sometimes it seemed to take me that long to organise the twigs I wanted to attach to my tapestry!  First there was the process of choosing the exact twig I wanted, then the colours, then the hitching, then the wrapping and attaching at the other end.  It could be recalcitrant and unwrap just as I was about to attach it - very annoying.  So I have been really appreciating the case moth species as I have been working.

There is much more interesting information on the site (linked above), so go and have a look.

1 comment:

parlance said...

I think that info about how the casemoth puts the stick in to its weaving is fascinating.