What Are White Grubs & How To Identify Them

White grubs are a common pest in home lawns that are considered one of the most devastating destructive turfgrass insects. White grubs are the larvae stage in the life cycle of scarab beetles. The larvae feed on the roots of the grass resulting in death of the grass plant or cause stress that creates wilting.

Throughout the grub life cycle, it changes appearance drastically in it’s shape, size, and colour. Here are the identifying characteristics to each stage of the grub life cycle:

Larvae

White grubs of all species have a cream white body and tan brown/reddish coloured head. The tail end of the white grub usually appears dark brown/black due to the soil they ingest during feeding. An arrangement of fine hairs are located on the tail that can be used to identify the species of white grubs. White grubs have six legs (3 pairs) located on their body just below the head. Their body is “C” shaped as they characteristically curl into this position when they are exposed from the soil. The size of  the larvae can vary between grub species and from the time of egg hatch (4mm) until they reach maturity (25mm).

Adult Beetle

When white grub larvae reach full maturity they become adult beetles. European Chafer, Japanese Beetle, and June Beetles (June Bugs) are common white grub species across many parts of Canada.  Adult beetles differ considerably in size, shape, and colour markings. The adult beetle life stage is not considered damaging to turf, however Japanese beetles can be troublesome causing damage to trees, shrubs, flowers, and other plant materials.

Raster Pattern

A raster pattern is used to identify the different species of white grub larvae. fine hairs that are located on the tail end of the larvae are arranged in distinctive patterns for each grub species.  for example: European Chafer white grub larvae have an “open Zipper” raster pattern that is used to identify them. Correctly identifying the white grub species is important so the correct timing and control methods can be determined.