marigolds

I am trying to set up some form of structure within the garden so as to include a variety of plants and decided to have some containers with Marigolds alone and the rest with a mixture of Marigolds and other varieties.
They flourished well for about three weeks then - disaster!
Every container had something eating away at the Marigolds alone. I set some slug pellets but there has not been one sighting of a slug near to the pots nor on the surface.
Anyone any ideas of what could be dining on my Marigolds but leave the other plants?

 

Any chance of a pic of the damage?

 

I'll be watching this thread carefully, because this year my marigolds also got eaten by something. I don't think it was slugs. One of my small trees got devoured by caterpillars, but I've only seen them on this one tree, and not on anything else.

 

Unfortunately I have cut out all the remaining bits that were left but, I can only explain the end result as having all the flower eaten away as well as about 95% of the leaves.
This was leaving a straggly stem formation.

 

This sounds exactly the same as what happened to my marigolds. I planted 18 and just within 3 days most of them had been eaten. I'm new to gardening and learning by my mistakes, so I don't think I'll be planting marigolds again.
After the event my dear ol' Mum informed me... Oh yes slugs love marigolds!
I can't use slug pellets due to the dogs and cats we have so I placed slices of oranges, which did attract the slugs and snails away from the plants.......sadly not enough to save the marigolds :( I went out under the cover of darkness many nights on a ''slug hunt'' and was amazed to just how many there were.......it was the tiny little slugs mostly that I found on the marigolds.
Not a very good pic but this is the remnants of my plants

 

I reckon that's what happened to mine. I'd put slug pellets down though. I guess the slugs preferred the marigolds to the pellets.

I hadn't heard of the orange slices trick, but I've read of (but not yet tried) many pet freindly slug control strategies. The beer trap sounds like a nice easy one to me. You sink a container such as a yogurt pot in the soil, leaving a lip of about 5mm sticking out so ground beetles don't fall in. Half fill it with cheap beer, then place a plastic lid over the top, using pebbles or such like to hold it about an inch off the ground so slugs can get in but larger animals can't. Apparently the slugs are partial to the odd pint of an evening, so on smelling the beer they go for a drink, fall in and drown.

 

I did try the beer trap once.......as soon as I turned my back, the dog drank it all!
Tried broken eggshells too.....around a Welsh Poppy, but that didn't work.