In article , The Devil's Advocate
writes
I don't know but there is a rule of thumb that comes from Gardeners'
Question Time and generally works well. If it's slow it's usually bad and if
it's fast it's a goodie. I think that's the right way around, haven't woken
up yet!

That's the right way round. Logic is that if it eats other insects (ie
it's a goodie, not a plant eater) it needs ot be fast to catch them,
whereas the plant eaters sit around sucking sap all day and don't need
to be fast.

You could wonder why they don't need to be fast to run away, but the
survival strategy for the species is usually to have a vast number of
offspring produced at short intervals so it doesn't matter if 99.9 per
cent of them are eaten.

--
Kay Easton

Edward's earthworm page:
http://www.scarboro.demon.co.uk/edward/index.htm