Red lily beetle or lily beetle

Control
Non chemical control
Where only a few lilies and fritillaries are being grown, the plants should be regularly inspected from late March onwards so that adult beetles, larvae and eggs can be removed by hand.

Common name Red lily beetle or lily beetle
Scientific name Lilioceris lilii
Plants affected Lilies (Lilium) fritillaries (Fritillaria)
Main symptoms Foliage is eaten by red beetles and their black excrement-coated grubs
Most active Late March-October

Chemical control
For extensive infestations, it may be necessary to use an insecticide, such as thiacloprid (e.g. Bayer Provado Ultimate Bug Killer), acetamiprid (e.g. Bug Clear Ultra), deltamethrin(e.g. Bayer Sprayday Greenfly Killer, Bayer Provado Ultimate Fruit & Vegetable Bug Killer) or lambda- cyhalothrin (e.g. Westland Resolva Bug Killer). Organic gardeners can use pyrethrum (e.g. Py Spray Garden Insect Killer, Doff All in One Bug Spray, Bug Clear Gun for Fruit & Veg, Pyrol Bug & Larvae Killer or Growing Success Fruit & Veg Bug Killer). Pyrethrum should control newly hatched larvae but will be less successful against the adult beetles.

Plants in flower should not be sprayed to avoid harming bees and other pollinating insects.

Found these, there are many more information online. Hope this helps a little.

They are the infamous Red Lily beetles. Pick off the adults when you see them, and be careful, they fall on their backs and are then invisible. Look out for the babies. They cover themselves in their own excrement. So you need to look for what appears to be messy bird droppings on the underside of the leaves. Wipe them off.
You can spray with Ultimate Bug Killer, but remember it also kills bees.

Snap

If you try picking them off manually it will not always be successful as you will miss those that bury themselves in the crown of the leaves. If the adults already laid eggs on the underside of the leaves they need to be removed too. It takes forever examining the underside of leaves on mature plants and removing eggs or larvae.

Just use a chemical spray in the late evening when there are less bees around. Pyrethrum, if you can get it or better still Permethrin (if you know where to get it as not available at garden centres any more) work well. As long as you avoid spraying chemicals on flowers the bees and other pollinating insects should not come to any harm.

Most folk just examine every day and squash 'em. Hold something underneath as they are bobbies for dropping off and landing brown side up so you can't see them on the soil.