Red or scarlet lily beetles (Lilioceris lilii) are pests that induces panic in lily growers because they can cause a lot of damage rapidly. Affected genus include Cardiocrinum, Erythronium, Fritillaria, Lilium and Nomocharis. They also eat the leaves of Polygonatum but do not lay eggs on them.
Lily beetle is native to Europe and Asia; it was imported to the UK becoming established in the late 1930's and has since slowly spread throughout the whole country. It has also become established in North America. Systemic insecticides like imidacloprid (Provado) give effective control. Other methods suggested by members of the PBS list: "spotting them with methylated spirits using a fine brush"; "I go out at least twice a day and inspect my plants and grab and smoosh the buggers"; and "rather than squish them, I drop or brush them into a cup filled with a solution of dishwashing detergent".
Click here to see other PBS list postings about lily beetle.
Photographs by David Pilling. Photo 5 shows dropping encrusted larvae munching away at a leaf.