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Processionary Caterpillars -

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Processionary Caterpillars



The larval stage of the bag shelter moth is a wooly caterpillar and their hirsute appearance plays
an important role in their unusual behavior. When they emerge to feed, they form a procession,
creeping along nose to tail in a colossal caterpillar conga line. Researchers at La Trobe
University managed to get to the bottom of this hairy caravan.


These wooly caterpillars are the larval stage of the bag shelter moth.

Being social little critters they nest together inside a silken bag nest. And something remarkable
happens when they come out to feed...

They form a procession, one following the other, head to tail in a creepy crawling conga -line.

Dr Martin Steinbauer and colleagues from Latrobe University wanted to know what drives these
caterpillar caravans forward and how they stay aligned. They expected it had something to do with
the caterpillars hirsute appearance.

First they observe how the caterpillars formed their procession. Twitching to locate each other.
Then full steam ahead.

Then some caterpillars a receive a haircut on either the first or last three segments of their body
before being re-introducing into the procession.

The inclusion of caterpillars whose hindquarter hairs had been cut caused the procession to break
down. Leader caterpillars become hard to follow and will not stop when those behind become
detached. But if the head capsule is trimmed the procession rarely brakes.

This study indicates that touch stimulus from the hairs is the mechanism that maintains the
single-file, head-to-tail movement.

So their locks are the reason they never get lost.