This is the worst year yet for me with SHB. The other day I was changing the oil in the oil tray under the SBB. I washed it out and filled it with water with some dish washing liquid in it. Checked it today and there was several dead SHB's in it. I don't know if it will kill the larva, hope not to have larvae anyway. But the grown beetles were dead in the tray. Did not measure how much dish washing liquid I put in, quessing, about 2 to 4oz in to appr. 1 gal of water. It is a home made tray for my TBH. Hope this helps.