Dick Chambers writes
I have lived in the same house in Leeds for the last 33 years. During the
first 27 (approximately) of these years, I hardly ever saw a snail, although
I did have a large number of slugs. During the last 6 (approx) years, there
has been a dramatic increase in the number of snails. On a wet evening after
dark, if I go to post a letter in the local mail box, my feet inadvertently
crunch a snail every tenth step, on average. I have just removed and killed
about 50 of them from my bed of petunias, the bed being a mere 5 square
metres in area. The snails are thick on the ground. It ihas reached the
point where I would describe it as a plague.

Is this problem local to Leeds, or has there been the same problem
throughout the UK? What has caused the sudden increase in their population?

I don't know about anywhere else (always had snails in Kent and Sussex,
but not in quantity) but same experience as you in Leeds - first few
years, slugs but no snails, now, lots of both.

The other thing that has changed over the period is that it has got
noticeably wetter. The stream in the Nature Area we look after has gone
from being a trickle to being a real stream, the boggy area in the local
park is now a real pool in winter and boggy most of the year, and there
has been a huge increase in plants like lesser celandine which like damp
conditions.

I can understand why this should lead to an increase in molluscs
generally, but not quite sure it should be the *snails* that have
increased - the shell, I would have thought, would make them better able
to cope with dry conditions. Though on second thoughts, perhaps the fact
they need a shell is an indication that they aren't as able as slugs to
cope with slightly(1) drier conditions.

(1) - we're talking relative here - nowhere in Leeds has ever been truly
dry ;-)
--
Kay