Dave, Imidacloprid is the gold standard, but can be very long-lasting. There are some new products in the Lawn and Garden section of your local garden store/feed supply that have this in them, in granular form, and that's what I've been using on my potted plants. It's essential never to use it on anything that might be edible to humans or other animals or where the pesticide can come into contact with frogs, such as the tree frogs in my greenhouse. My preferred method is repotting, with the old contaminated soil sent to the garbage bin or treated in my compost pile that is strictly for the ornamental garden. Others on this forum can give you a better idea of dosing for these products, as I recall. I know this is a bulb forum, but I also know that many of you grow a lot more than just bulbs. How safe this product is for your Euphorbia is best answered by others. Robin Hansen Hansen Nursery North Bend, Oregon