One thing I do in the evenings, while I’m out walking and photographing insects that I see, is killing Japanese beetles (Popillia japonica) that I spot. It seems like the primary host for them on my property is multiflora rose (Rosa multiflora), with eastern redbud (Cercis canadensis), brambles (Rubus), black willow (Salix nigra), and frost grape (Vitis vulpina) being notable host plants for adults as well. I wonder if my hand-picking really does any good at all, especially considering I can’t reach some spots, particularly on the multiflora.
Over the past year, I’ve tried cutting back the multiflora roses that I could, while trying to introduce swamp rose (Rosa palustris) next to my pond to fill the gap. I wonder what effect, if any, removing all multiflora rose from my property would have on the Japanese beetle population. Also, is there any pheromone trap which actually works for killing them? Sometimes I hear that those traps just attract more and don’t do a good job with actually killing them. Is the parasitoid winsome fly (Istocheta aldrichi) hopeful for a biological solution?