There is only one good thing about the lily beetle : you can see them easily. Once the lilies start coming through I check on them several times a day. Almost without fail I find one or more of these beasts. They are very nifty at dropping off the leaf at the first sign of danger (ie me) but I have developed some equally nifty techniques at catching them.
I usually have a small container of some sort so that I can just knock them in. They fall on their back and I can then pick them out and kill them between two stones.
If I don't have a container I try to arrange things in such a way that they fall into my hand. Then again the trick with the stones.
Be warned, these beasties can fly away. However, if they are on their back you usually have the upper hand.
Why are they so horrible? They lay their eggs on the underside of the lily leaf and the larvae hatch in what appears to be poo. The larvae then eat voraciously, weakening the plant to such an extent that the flowers are severely stunted.
I am always open to suggestions of a positive nature. If anyone wants to give me just one good reason not to squash these red pests, I will listen carefully.