Asked by: Geoff Stevenson, Swansea
Snails find it much easier to move on wet surfaces than dry ones. In dry weather they will tend to avoid pavements, in favour of undergrowth, which retains moisture better. Once the pavement is wet though, this aversion is greatly reduced and snails can easily stray onto the edge of a pavement. Since there is nothing much to eat there and the bright light makes them more vulnerable to predators, they tend to keep going in a straight line, not realising that this will take them straight onto the road.