Actually whilst repairing my greenhouse last year because I found some rot under the wooden eaves. I actually found that many earthworms has actually climbed the front of the greenhouse and were living in the rotting wood. Just think I could have had the first greenhouse ever destroyed by earthworms. No prizes for guessing but the only way they could have got there is by migrating from pots on the greenhouse shelf. So yes bigger problem than I first thought, and don't we all read how beneficial worms can be ! I'll just have to take up fishing, now that could solve the problem and there would be little need to buy bait. Best Wishes, Dave