Wheat Insects

White Grubs (Scarabidae)


Adult Phyllophaga sp.


Phyllophaga sp. grubs.

White grubs are the larvae of scarab beetles, often known as May or June beetles. Larvae may damage plants in either fall or spring, feeding on the roots or cutting off plants below the ground. Losses may become significant when there are four to five grubs per square foot. However, there are many species, and not all are damaging to wheat, so concern is only warranted when stand loss is evident in conjunction with the presence of grubs. There are no insecticides labeled for white grub control in wheat. However, systemic seed treatments that incorporate imidacloprid (Gaucho and others) and thiamethoxam (Cruiser) may provide some suppression because they are labeled for white grubs on other crops. Larval feeding ceases with the onset of cooler weather, so delayed planting can reduce stand losses.

Page last updated 10/31/2013 by J.P. Michaud.