Those of you plagued with green fig beetles, aka green June beetles, may find this easy-to-build trap useful. I found the basic idea online but thought step-by-step directions might be helpful:
1. Cut both ends from a 2-liter soda bottle, creating a funnel. The "neck" hole needs to be big enough that beetles can easily fall through.
2. Make a plastic baffle that fits snugly into the soda bottle. I cut two rectangles from a plastic ice cream tub, with a narrow slit halfway up the center of each so they could fit together in an "X" shape. One of the online sources said traps with bright colors at the top worked best, so I painted some decoy "fruit" dots in different colors. I don't know if it really helps, but it might!
3. Using the wide end of the soda bottle funnel as a guide, use a Sharpie to draw a rough circle around the neck of a gallon milk jug--avoiding the handle. Then cut the circle out with scissors, taking care to stay inside your line far enough that the soda bottle will fit snugly into the hole. It doesn't need to be perfectly round--the bottle will conform to the shape. Then cut a couple of narrow slits in the sides of the milk jug, about 1-2 inches up from the bottom. These will allow rainwater to drain out.
4. The critical part is what to use as bait. In years past, I've tried similar traps with no success--using over-ripe fruit that beetles had already been eating. The online source I read recommended isopropyl alcohol, with some grape juice mixed in. Rather than pour it into the bottom of the jug, put it in a small container with a hole drilled in the lid for a wick. I used a pill bottle with a rolled up a paper napkin for a wick. To keep it from falling over, I stuck it in the lid of a spray can, which I snipped into a daisy shape to keep it from filling up with gunk. The snipping was probably not useful.
5. Fasten it in, or near, a tree where beetles like to hang out. Don't do what I did, and tie it to something--because when you want to dump the stinky, drippy dead beetles it's a pain to have to untie a knot. Now I use a spring-loaded clamp to clip it in place. The final step (best done after it's in place) is to put 2-3 drops of dishwashing detergent in the bottom, and then pour in water till it starts to dribble out the slits in the jug. The detergent water will quickly drown the beetles.
That's it. Check it every couple of days, because soapy dead-beetle soup is super stinky, and probably won't attract many new beetles. Unclip it, pull out the funnel and dump the beetles, hose it out, and reset it. This year it was just an experiment to see if it works. It does. Now I'll start saving milk jugs & soda bottles to have a bunch of traps ready for next year.