Definitely slow release pellets. No pest in Britain has eggs of that size or colour. Mollusc eggs are clear or milky and all the other pests eggs are too small to be seen with the naked eye.
As I said, whilst vermin might dig under the bulbs, the bulbs themselves are poisonous. So any mouse which ate one would pretty soon die.
I would see if I could find a bulb and see if there was a Narcissus rootfly grub in it.
Aphids which come in all colours including black. then they are called blackfly. Spray with something which kills them. Lots of choices of aphidicides
When was the image taken?
We would have all of them, but sadly even here we have run out of space. Even pruned they do make big shrubs.
I also like H, grandiflora, which is very similar. H,g Red Annabelle is rather nice.
No favourite, I like them all, even the one which has died three times on us. Japanese place name. Memory has gone. Actually I do have a soft spot for Vanille Fraise though.
We cut ours back to a pair of healthy buds about 25 cms above the ground. (10 inches). Feed them and they soon throw up good shoots which flower.
We do this with all 12 of the H. paniculata we have. About now is the time too,
Don't actually have a picture of the view from our garden at present. Would be a bit like Lou's if I could get up high enough.
There is nothing you can do to prevent it, other than plant deeply.
We have over 100 Clematis in the garden and I have never seen wilt here, even in the most susceptible types.
Very country. Soil is silt/peat. Very windy garden. Frost pocket. Half the national average of rain (except this year). Fast draining very rich soil. (ex outdoor reared pig farm.
Been a garden or sorts since the 1640's.