I squish them with my fingers. They stand out against the green. I check each day.

Yes, that's what we all do on here. No short cuts I'm afraid. And take care as when they fall off they land upside down and are brown underneath and hard to see so put something underneath before you try to get at one! and you could look for the little brown caterpillar like larvae on the underside of the leaves as well if you want.

My lilies have finished flowering now and the stems have been cut back to about 12 inches. Mine were attacked by the red lily beetle severely this year and, as far as I know, there is no spray that will get rid of them. As stated the only way is to crush them between the fingers....however you have to check them over at least twice a day.

I use Provado Ultimate Bug Killer. It was recommended by the chief entomologist of the RHS at I talk I went to a few years ago. If it's good enough for him ....

Provado is a nicotine derivative, persists on edibles and is very dangerous in water courses so if you use it take extreme care, and only then as an absolute last resort.
Interesting that the RHS recommend it.