Japanese beetle (Popillia japonica) traps are very effective in monitoring their presence but not in reducing their numbers. "The issue is that they work too well in this regard, causing more beetles to arrive than the trap can hold," says Emily Althoff, a Ph.D. student in entomology at the University of Minnesota. "However, the commercial traps are not designed to kill enough beetles to make a difference in damage rates in agricultural fields or gardens. We did count the number of Japanese beetles that bucket traps hold and found that approximately 3,500 beetles fill the trap. The traps are so effective at attracting Japanese beetles that they can fill up in as little as two days." (Photo by Raymond Cloyd, originally published in Althoff and Rice 2022, Journal of Integrated Pest Management)