[AlaninCarlisle]

What could be eating the leaves of my cucumber seedlings in the heated propagator? It leaves alone the other stuff in there like tomatoes, beans, celeriac and courgettes.

[8doubles]

If in doubt blame a slug !

The pest may not be specific (this is not a good country to be a cucurbit only eater) slugs and snails will often eat one plant completely before starting on the next.
Have you crept up on it ninja fashion late at night to find out ?

[AlaninCarlisle]

No, but I've just this minute put slug-bait in there, so we'll see what happens