the recommended treatment is to pick them off and squash them. a possible pesticide is Bio Provado Ultimate but this contains a pesticide which is though to cause "colony collapse" in honeybees, which is a major problem

I googled this after what you said Mageth. It looks like this has been known for some time. Even as far back as 1995. Provado introduced more recently contains same chemical. I also googled Red Lily Beetle . I picked off what looked like a piece of dirt this morning. There are photographs of this maggot, which is red to start with, then coats itself in its own poo and gets busy on the lily LEAVES.......so those bits of dirt need squashing too. They go through their cycle very quickly and a piece of poo can be a red beetle soon after, mate and so on and on......

Yes they are disgusting, but relatively easy to spot and remove by hand

My only advise is, as already been said, to check over the lily every day- twice a fay if you can- and pick off the bright red beetle and squash it betweenyour fingers. It's the only way.

I have one regal lily left and it has grown well this year. So far not attacked but it will be. They even stick around to chew up one plant! More publicity very recently about nicotine based products being involved on the shortage of honey bees due to colony collapse. More recent investigation allege these products are harming bees.