Bag-shelter Moth (Ochragaster lunifer)

 

For about a week I've been watching these caterpillars as they crawled up the wall after some heavy rain. (This is my next-door neighbour's condo.) First of all they were all bundled together in one big mass (didn't think of taking a photo on the first day), but the next day I found them walking up the wall in straight lines.

Why do these caterpillars go in a line? They travel in long lines of hundreds or more in search of food or a suitable place to begin the transformation into their adult form : the Bag-shelter Moth. Together they present a formidable number of irritant hairs to predators and the conga line helps prevent them getting lost.

It is also thought that they walk in line to scare off predators who might think it is a snake. How clever!

These caterpillars are grey and hairy with a brown head. They grow to a length of about 4cms. When they mature, they will descend from their tree (or wall, in this case) to pupate in a silk cocoon in ground debris, and what hatches is the Bag-shelter Moth.

I have actually found that not many birds like to eat this moth. When touched it curls up, showing a black and red body, which I presume signals that it is poisonous.

By day three the "train" had moved higher up the wall, heading for the roof, it seemed.

Note the bunch of caterpillars behind the Sansevieria close to the ground.

For another day or two they kept on "clustering" and forming trains until eventually, all that was left was a few stragglers - I presume that the rest had descended to complete their pupation.

By the way, lots of caterpillars together is called an "army". These ones are also called Processionary Caterpillars or a "train".

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