When Should I Apply an Insecticide?For potential surface feeding insect problems, an insecticide may be applied as a preventive treatment. For example, Chinch bug damage is most common beginning in May and continues throughout the summer. Typically, the insects can pose a problem in areas of full sun. If preventive treatments are not desired because of cost, the insecticide needs to be applied as soon as damage occurs.
To control root or underground feeding insects like grubs, insect control products may be applied in late July and into the months of August and September. It needs to be thoroughly watered into the soil after the application to ensure its effectiveness. The small, immature stages of adult beetles are the easiest to control as they are located closest to the soil surface during the late summer/early fall. Spring applications of insecticides are generally less effective because of the larger size of the grubs and because the grubs are located deeper in the soil.