Bad advice -(You'll need a grub
product if there is more than one grub per sq foot.)

One grub per square foot is far below the action level for applying
grub controls.
10 or more grubs/sq ft is more appropriate.

A good product to control Japanese beetle and a few other species of
grubs is called milky spore which is a bacteria that specifically
targets them. It takes a year or two to work fully as the spores
reproduce inside the grubs to reinfect more grubs as long as they
occur.
Benneficial nematodes are another approach.

Setting your mower to cut the grass at about 3" high will do much to
control weeds
provided you mow often enough to keep the weeds from setting seed.
Adjusting the soil pH will also allow the turgrass to outcompete the
weeds.
A simple pH test is cheap and many garden centers will do it free.

In the Northeast where cool season grasses tend to go dormant during
the hottest part of summer the beetles prefer to lay their eggs in
turf that is irrigated. Simply allowing the grass to be dormant during
this peroid by suspending irrigation
will send the next generation of grubs to the neighbors who irrigate
during this period.