Cuttings: Slugging it out

PATRICK Braddell writes to say that in his experience, grit is no deterrent to slugs (Gardening, 25 September). 'I have a considerable collection of cacti in my glass house which seems to double as a dining club for slugs and snails. The pots stand on gravel and the plants are top-dressed with granite chips, but I still find slug and snail trails all over very prickly numbers, even rebutias. On cacti with minute, almost spineless areoles, the miscreants take out the growing tips. I would guess that slug and snail trails act as a lubricant and an insulator.'