lettuce being eaten from below also my strawberrys help

Hi can any one help I seem to be losing my lettuces and strawberries over night almost.
I water well after the sun has set on my vegie patch. When i get up in the morning the top leaves are all brown and dying. over the last few days I have lost half my stock and the others are looking weedy!!!
many thanks

It sounds like scorch to me, rather than slugs/snails. Where abouts are you based Racheir?

it has ben very warm but i have been careful when i have watered. I am in lincolnshire. ps its like they have died at the base of the plant and are all brown. Aunt sally wat are the wormy things and how do i check if i have them?