HiYield Kill-A-Grub Is The Safest, Most Effective, Easiest To Use Grub Control. Labeled safe for schools and playground use. Also controls Armyworms, Sod Webworms, Cutworms. Controls surface and soil pests. Use at higher application rate for grubs. Does not require immediate watering, however, if you have a dry spell, do water in as it will not start working until it is watered into the ground. Timing is very important. Here in the upper MidWest Kill-A-Grub needs to be applied in July to early August. Kill-A-Grub is only effective on the first two instar stages of the grub. If you wait too long it will not work. Kill-A-Grub speeds the metamorphosis cauing the grub to be disformed and die. Will not harm people or pets. 17 Lbs. covers 5,000 sq. ft. for grub control.