It’s just not summer until the “yard art” Japanese beetle bags are put out, decorating the lawns of America. Unfortunately, these bags can cause more problems than if they’re just left at the store.

Adult Japanese beetles don’t just stop to smell the flowers – they attack plant foliage.

Photo Credit: ©2005 Buglady Consulting

For those not familiar with the “bag traps,” they’re kits containing a long, slender plastic bag with an attractant. They’re used to draw and trap only the adult Japanese beetles that have been eating their way through your garden.

How do the traps work? The bags are hung on a stand (usually sold separately) and then baited with a combination of a pheromone (or sex attractant) and a floral lure. This combination attracts both male and female adults to the trap. As the beetles are drawn in by this chemical aroma, they try to land on it. But being the weak flyers that they are, they end up crashing and falling into the bag. Once in, they’re trapped and die. This seems great in concept – trapping the beetles prevents them from feeding and laying eggs – but research has shown that these traps may not be all that great after all.

The studies show that bag traps attract many more beetles than are actually caught in the bag. What this means for your yard is the plants growing along the beetles’ flight path and in the vicinity of the traps are more likely to suffer damage than if no traps were ever used at all. The bottom line is even though you feel great because you appear to be attracting and killing hundreds of beetles in the trap, you’re only making the problem worse for your lawn and garden.

What these bags are good for, though, is assessing the Japanese beetle population in a given area. If you’re not sure if the beetles are out, just hang one of these bag traps, and then you’ll know for sure.

Japanese beetle bags seem great in theory, but they can end up causing more of a headache in the long run. Other management practices – like pesticide sprays for adult insects, beneficial nematode applications for Japanese beetle grub control and resistant plant varieties – can be better used to help fight the battle against this hungry beetle.