Abstract: Abstract This test was conducted at the Main Station Field Laboratory at Reno on an 8 year old stand of alfalfa var. Ranger. Each treatment was applied to a 4 acre block of alfalfa on May 5 with a tractor mounted John Bean field sprayer(pto) with a 24 ft boom and calibrated to deliver 25 gpa at 25 psi. At time of treatment the field was unifbrmally infested and begining to show severe symptoms. On each sampling date aphids were sampled by both sweep net and stem counts. Each treated block was subdivided into four sections and sampled on each date by taking 10 random 180 degree sweeps with a standard net and 20 stem terminals.