A couple of years ago guys were talking about making traps out of plastic 55 gal barrels. I tried it but I must have gotten the discription wrong. They never went into the barrel.

The bait attracted them all to that one area and I ended up walking around with a hand sprayer and Malithion. The next day the ground was covered with dead beetles. Put the bait in a soybean field where its easier to walk around. It will draw them out of the corn.