They have 6 prominent legs, well formed for digging, not walking. The head is brownish and armed with a powerful pair of mandibles. White grubs vary in size from 5 mm when first hatched to over 2 cm when fully grown. Bacteria in a large hindgut caecum break down plant material. Through proctodeal feeding, these bacteria are ingested and digested by the grub as a protein source.
White grubs are subterranean in habit, feeding on the roots of young plants.
Damage can be detected when seedlings turn sorrel red and die as a result of larvae shearing off the plant roots. Larvae generally live for 2 years, doing the greatest damage in their second year. Larval damage to seedlings in nurseries has been recognized as a problem for over 50 years. Not until the 1940's did it become evident that grubs might also be a threat to forest plantations. See HyperNur .