Grazers G4 is thought to be a more environmentally benign treatment to tackle Red Lily Beetles. Please read the labelled bottle carefully before applying to plants.
Neem oil can be applied as an alternative to the latter. It's not appropriate for use if the lilies are near a water body because it can be toxic to aquatic wildlife.
There are also more persistent chemicals available for use on the market. Lambda-cyhalothrin, deltamethrin, and cypermethrin are a few of the active components that can eliminate Lily Beetle larvae. The latter should only ever be used if an infestation is considered heavy.
Likewise, any plants that are in flower, or near a water body, should never be sprayed by the latter to protect pollinating insects.
It's best to apply insecticides earlier in the season when larvae are most active. Assess whether chemical treatment is essential. Towards the end of the warmer season, Lily Beetles begin to move away from lilies to overwinter. Applying chemicals at this point would be ineffective and wasteful!
Please read and follow the manufacturer's instructions before any products are used.