How to Control Scarab Beetles. Controlling scarab beetles is a year round job that requires considerable vigilance. Both the adult and larvae are resistant to most insecticides and the adults are capable of flight, which expands their territory quickly. Scarab beetles strip trees and other plants in swarms that travel during night making them difficult to control.
Employ insecticides that contain dimethoate. Spray tree trunks and surrounding vegetation before dusk to catch sleeping swarms. Residual chemical effects are unlikely to kill the beetles directly, however egg production is reduced.
Introduce scarab beetle traps, also called light traps, around property susceptible to damage. Scarab beetle traps draw the beetle into a box with a glow light. The beetle pushes a roller in the top of the box to gain entry, the roller flips over and seals the box.
Cultivate soil regularly to kill larvae and expose them to natural predators such as magpies, which consume large numbers of scarab beetles when available.
Control weeds to remove nesting areas for adult beetles. Spray a light soap and water mixture on problem areas when chemical use is undesirable.
Plant beetle resistant trees and shrubs for long term control. Remove dead or sick plants to minimize the feeding attraction of the property.