Fred the Thread

Dr Robert Hoare, of Manaaki Whenua – Landcare Research, tells the story of Fred the Thread, the world’s thinnest caterpillar. Join the detective hunt for this elusive species.

Transcript

DR ROBERT HOARE
Fred the Thread was discovered by a colleague of mine, Corinne Watts, and she was studying a peat bog in the Waikato area, and these peat bogs are very special habitats. They are the only place in the world where you get this giant cane rush, which is called Sporodanthus in Latin. The peat is actually mined, and the mining of the peat destroys the habitat, and the people who mine it have to restore the habitat. What Corinne wanted to do was find some insect that was specifically associated with that giant cane rush. So she was searching for insects, and she discovered these little tiny mines in the stems, which were like a little squiggle on the outside of the stems. And she opened up the stems to look inside to see if she could find what was making those little squiggles, and then eventually she discovered little tiny larvae – very, very thin and less than a millimetre thick, but up to about 3 centimetres long. I thought it was far too thin to be a moth caterpillar, so I gave it to our beetle specialist thinking it might be a beetle larva, and he said, “No, it’s not a beetle, but it might be fly”. We couldn't find any fly experts to see whether it was a fly maggot or not. So eventually Corinne and I decided that we were going to go down and sort out the mystery ourselves once and for all. So we went down to the peat bog and we just collected a whole heap of stems of Sporodanthus, put them in a closed plastic bag and just kept a close eye on it and waited for things to hatch out. And eventually a moth hatched out. It was very exciting to find out it was a moth because it meant it was a new species, and it meant that I got to name it. And it was a very unusual discovery because the caterpillar was so thin, and in fact we believe it’s the thinnest moth caterpillar in the whole world.

Acknowledgements:
Dr Dave Campbell, Department of Earth and Ocean Science, University of Waikato
Neil Fitzgerald, www.neilfitzgeraldphoto.co.nz
Invertebrate Systematics, CSIRO Publishing https://www.publish.csiro.au/nid/121/issue/2003.htm
Jan Ramp, Snapper Graphics
Birgit E.Rhodes, Manaaki Whenua – Landcare Research