Try a cheaper vegetable oil, floated on top of a splash of soy sauce.

Or, go out there at night and hit them directly with insecticidal soap. It kills
them very quickly. Also hunt around by day for their hiding places, and hit
those with insecticidal soap.

One foot pieces of plastic water pipe laid down in the mulch can trap them.
Tap the pipe into a bucket with soapy water to knock the earwigs out and
kill them. (Dampen them before you lay them out.)

Last night I tried Canola oil (hey, what can I say, I try and eat
healthy!) but still got the same disappointing result. Zero
particpants in the swimming pool o' doom.

I'll move on to the cardboard, the hose, and the soap tonight. These
little buggers are decimating my Butterfly Bush, not to mention my
Hollyhocks!

Thanks for the suggestions.

-Fleemo