only in the spring and fall when there are active grubs. to prevent then put down "merit" in the summer but don't wait until august to do it because Japanese beatles lay there eggs and they hatch into grubs around that time and merit wont kill active grubs. Arena is awesome because it also kills surface insects like sod webworms and chinch bugs which also cause turf damage. put down Arena in late august and you will kill all turf damaging insects which includes surface and sub surface insects.
How often to apply? this stuff is $$$ but it works great
only in the spring and fall when there are active grubs. to prevent then put down "merit" in the summer but don't wait until august to do it because Japanese beatles lay there eggs and they hatch into grubs around that time and merit wont kill active grubs. Arena is awesome because it also kills surface insects like sod webworms and chinch bugs which also cause turf damage. put down Arena in late august and you will kill all turf damaging insects which includes surface and sub surface insects.