Japanese Beetle traps, Part II

About 10 days ago I placed five Spectracide^® Bag-A-Bug^® Japanese Beetle Traps around our yard. They immediately began filling up with Japanese Beetles, which is the desired effect. The question is, are they effective in reducing Japanese Beetle populations on the plants that are infested, or do they merely attract Japanese Beetles from all over the neighborhood, creating a bigger problem.

This is what I found:

1. If the traps are placed up wind from the infestation, the Japanese Beetles will swarm around the trap. It is important to shake the plants out and decouple any of the mating bugs as the trap works with a sex lure (I assumed that the bugs already having sex would not respond to the lure). I also noticed that several birds were hanging out around the traps catching the flying beetles and eating them.
2. Buy more traps than you think you will need and space them out around the yard. This gives you a good idea of problem areas where grub treatments can be most effective.

The worst area in our yard seems to be the patio and grape trellis. The grape vines were heavily infested and they are looking a little ragged as a result. Before placing the trap up wind of the grape vines, each vine would have about 20-25 Japanese Beetles on it every morning.

This morning I checked how many beetles were on each vine; two of the vines had none, one of the vines had one and the other had five. I would call that a very good result.

The trap closest to the grape vines has had it’s bag changed twice. All of the other traps are still on their first bag. This is a great indicator of where additional treatments of milky spore will do some good. Last year I put it down mostly in the front yard, which was turning brown because the grubs were eating the grass roots. The trap in the front yard near the peach tree has some beetles in it, but less than the other traps. This is good empirical evidence that the milky spore is working.

Conclusion:

The Bag a Bug traps work at killing Japanese Beetles and when placed correctly (by following the directions that come with the trap) they can be effective in reducing Japanese Beetles around the yard. They can also be used as a guide to where grub treatments can be used most effectively. I recommend NOT using insecticides like Grub X or other chemical based treatments as they kill all the stuff in the ground doing more damage than good. They also get into the food chain and can pollute water systems. Milky Spore is a bacteria that multiplies in the soil. It only effects Japanese Beetle grubs and once established can last 20 years.