Q: We have a sixty acre farm, a 4 acre fenced yard and a swimming pool.
For the past six weeks, I have been netting HUNDREDS of grubs out of my pool every morning. Sometimes a couple of thousand crawl to the pool at night and drown. We have lived here 10 years and never encountered this problem.
This past June and July there were thousands of June bugs and Japanese beetles in my yard but that is common every year. These grubs are not destroying my grass but I can see their holes.
A: Wow – if you hadn’t sent pictures I never would have believed you!
Undoubtedly the grubs are those of green June beetles. Unlike Japanese beetle grubs, these creatures mostly eat decomposing thatch and don’t do much damage to grass roots. Their tunneling in the soil loosens it and allows it to dry, which harms the grass. Mature grubs come to the surface in the evening and feed on grass blades. The results of their movement at night is what you see in your pool.
My recommendation is to apply grub control insecticide granules in a twenty foot wide band around your pool now. Next July, use imidacloprid (Bayer Advanced Grub Control) or halofenozide (Mach 2, Grub B Gon or Grub Ex). Be sure to water afterwards to move the insecticide into the soil.