I've heard lots of people having problems with these and my very first lily 'Matrix' got eaten at this year by them. So next year, I'm going to pick up some Neem Oil, which I've heard all across the board that it works (aside from the usual picking off the parents from your plant). Now I don't know plenty about bugs on plants, but I was recommended that to get the parents, you put newspaper down under your plants, leave and let the bugs go back up on the plant. Next time you come around, give your plant a little shake to get the beetles off. Though from what I hear, they fall on their backs when they see you coming and blend in with the dirt. The idea is to catch them in the newspaper and wrap em up! Take those suckers away.
Someone on a site mentioned using Bayer Rose? Or Garden spray and Bonnie Punch began what they like to call a 'soap box' lecture which I found really informative and wanted to repost what they said:
"Diazepam is a sedative that is more commonly known as Valium. The active ingredient in Bayer Rose and Garden Spray is Carbaryl.
Bringing it across the border into Canada is likely illegal.
There are several problems with recommending this spray. Firstly it is banned in many places. The entire province of Quebec has banned its use cosmetically, as have more than 60 municipalities across the country. Why it's banned - it's highly toxic to honeybees and other beneficial insects, moderately toxic to many species of fish and wild birds, and moderately to very toxic to humans when it is inhaled or ingested. Contact with the skin can cause burns, and it is readily absorbed through the skin. It is a cholinesterase inhibitor, which means it is a neurotoxin. Prolonged exposure has been linked to birth defects in some animals (including humans), and it is a suspected carcinogen.
Carbaryl has a half life of 3-10 days. That means you have to spray again after that because the chemical has broken down.
The threat to honeybees is probably the most severe one. Honeybees are declining in extremely rapid numbers, and they may be in danger of becoming wiped out in North America. Bees are the most important crop pollinators we have. If you eat an apple, have cereal containing grains, veggies with your dinner, you are eating foods pollinated by bees. Even the steak or chicken breast on your plate was fed by bee pollinated crops.
So before you dust your lilies, please think about what else you may be killing. "
Neem Oil seems to be the safest way and you can get it online (also recommended by another poster) http://www.ghorganics.com/SupremeNeemOil.html
Just a thought for the day, especially for next year in using preventive measures for bugs and such.