Sarah Webb, of Rangiora High School, asks :-

Are all earth worms native?

Jo Springett, a soil zoologist at AgResearch Grasslands, Palmerston North, responded.

Thirty-five years ago there were about 200 different species of earthworms in New Zealand. There may be fewer now as some may have become extinct since then. Of the 200 species about 20 came to New Zealand by accident from Europe, in soil on cargoes of potatoes or mud on cart wheels or with trees and other plants which early settlers brought with them. Most of New Zealand now has one or two of these LUMBRICID species and they can be very numerous in pastures.

The other 180 or so species are native New Zealanders. The native worms are MEGASCOLECIDS and mostly live in places where there are remnants of native bush. A few species are able to live in pastures and in gardens. Native earthworms range in size from two centimetres up to one metre long. The latter, Spenceriella gigantia, have been reported only in northern regions.

Some of the native species are bioluminescent in that they emit light which comes from the slime which they secrete through pores along their back or which leaks out of a damaged worm. The Maori use these worms as a fishing bob as eels are attracted to the glow of the bob. I know of two earthworm species in the Manawatu which glow. One is probably the one you call the milk worm and is quite common in pastures. Its name is Octochaetus multiporus, the other is found under trees and is called Rhododrilus edulis.