Updated: Nov 7, 2021
I mentioned the little lily beetle in June's "things to do" blog: https://www.jardinpaysan.com/post/some-things-to-do-in-the-garden-in-june. This pest is a serious predator, targeting mainly lilies but also fritillarias, lily of the valley, Solomon's seal, hollyhocks and even potatoes. It originated in mainland Europe but is now a menace world wide.
The beetle sounds a rather sweet little thing from the way I described it - It is so pretty that I nicknamed my car after it - my car has a bright red roof and a brownish bottom half. However, there the comparison ends. Apart from the fact that is can totally decimate your lilies, it really is a disgusting creature and this year it has targeted our garden where we grow all of the above mentioned plants. So far it has not strayed beyond the lilies which I grow in pots.
While accepting that every one of us is entitled to our space on this earth, I do wish the lily beetle would clean up its habits and move somewhere else.
If you do not manage to pick off and squash every single beetle (pretty much impossible), then they will lay eggs on the underside of lily leaves and within about a week these will hatch out into slug-like larvae. Just as the beetle itself has discovered a way of evading predators, so too have the larvae. This is what they look like and what the damage looks like (a rather blurred image, I am sorry, but you get the idea):
For about the next three weeks the larvae will eat their way through the lily leaves. While doing so they camouflage themselves (and make the job of picking them off totally repugnant) by covering their bodies with their own poo. I remove them and their eggs by wearing rubber gloves and washing them off in soapy water. Survivors develop into adults over a three week period. These eat a lot more of your lilies, although the larval phase is the most destructive, and then overwinter in the soil beneath the plant - ready to start again next year.
We grow our lilies in pots and I think that this year, once the lilies have died back, I will remove the soil and burn it. Next spring I will replant them in new compost. I don't suppose this will completely eradicate them, but hopefully it will give me the upper hand.
I also hope you haven't read this just before going to sleep for the night - it might give you nightmares.
Further reading, for anyone who wants to know more: