Nematodes for chafer beetles?

I’m wondering if anyone here has gone the nematode route to deal with chafer beetles? We’ve had a bad case of these beetles in one area of our place, where we’ve got quite a sandy mineral soil under the topsoil.  And both raccoons & skunks dig many holes, down three to four inches, for the beetle grubs there — looks like a rototiller has worked-over the ground! (And not in any good way!)

So, this past spring we purchased a packaged slab of nematodes (brand name “Attack Pack”), and you mix it thoroughly into water then water the area with this activated solution. The directions cautioned to wait until the air temperatures were running above 12* Celsius, which we did. Also, they cautioned to do this at a time of day when there’s no significant direct sunlight. I really soaked the affected area.  As you need to maintain ground moisture after spreading the nematodes, when nature didn’t provide some rain we used sprinklers.

Unfortunately, the treatment doesn’t seem to have worked, as the skunks (at least) are back & I’m having to trap them one by one… but only caught two so far, and I strongly believe there is a third around.