A drench test can be performed
to detect the presence of adult and larval insects that feed below
the soil surface. Mix 1 to 2 fluid ounces (2 4 tablespoons)
of liquid dish soap to a gallon of water. Two gallons of water may
be necessary where soils are dry.
Test an area of the lawn that includes both healthy and unhealthy
grass. Mark one square yard of lawn off with a piece of rope and
apply the solution as evenly as possible over the area with a sprinkling
can. The soap solution will cause insects to move to the surface.
Identify and count the presence of any insects within ten minutes
of performing the test.
*White grubs and billbug larvae are monitored through digging.