[aelf]

One by one they are being stripped by a mystery pest which eats the greenery and leaves the thicker white veins. I have netted and put slug pellets down with no noticable effect. I've inspected the plants closely and can't find slime trails or caterpillers so I'm at a loss to explain it. 

Any thoughts?

[Aunt Sally]

Check your nets for any holes.  Pigeons will go in if there is a gap to get through 

[Irene]

aelf:

It sounds like pigeons to me. I had the same thing happen last week...maddening.

[Comfortably Numb]

Definitely sounds like pigeons to me.
They are either getting through a hole, or maybe underneath the netting if it isn't pegged down securely.

[aelf]

It does look like pidgeon damage but I can't see how they are getting in!  I also wondered about rodents? I know the site is overrun with them - I even saw a field mouse sunning itself on the path the other day 

[Anton]

I don't grow cabbages but a woman who did had her leaves eaten year after year (for about three years, that is) and I invariably told her (because she always forgot, or she was teasing me) year after year to cover them with the tops of plastic water bottles, which she invariably did and they always recovered. In her case it was the slugs that did it.

Anton

[DavidT]

Keel slugs, tehy live in the soil, come out at night to dine, then tucked up back in bed before sunrise.  They leave no trail, and as the are only about a half inch long, they tend to go unnoticed.

[Livinhope]

Are those the tiny black slugs that  live underground.  I have had a couple of broad beans and potatoes go over and when I looked it was these little slugs about an inch down still attached to the stalk.

[kingdhesiii]

TIME FOR NEMASLUG !!!!!!!

[Aunt Sally]

a mystery pest which eats the greenery and leaves the thicker white veins.

This is absolutely classic for pigeons !

[aelf]

Thanks for the replies. I checked the netting last night (very carefully) It seemed fine to me but I pinned it down with lots of extra bricks anyway. There is still something eating the cabbage when I checked this morning so, unless there is a crack SAS team of pidgeons working together to get under the net, I guess it must be slugs  Little blue pellets everywhere now!