Grub Worms in Soil

Description

• Soft-bodied grubs are dirty white in color with brown heads and six, sturdy legs. The pests are about an inch or slightly longer, depending on the species, and lie on their sides in a C-shaped when disturbed. Grubs are identified by the distinct pattern of spines on their abdomens. Some other distinctions also exist by nature of species. For instance, the grubs of the June beetle have weak legs.

Damage

• All grubs infest and feed on grass roots. Damage appears in the form of thinning, yellowing and eventually dead grass patches. The irregularly shaped patches get larger as damage progresses and the water and nutrient conducting ability of the grass is affected. Grass pulls up easily and often rolls like sod. Grubs also invite secondary pests such as birds, armadillos and raccoons to the garden that inflict serious damage as they dig through lawns in search of grubs.

Biological Control

• A number of biological control options provide effective grub control. Introduce grub-feeding natural predators such as ants, ground beetles and parasitoids such as scoliids or parasitic wasp larvae into infested soil. The use of commercially prepared insect parasitic nematodes from the Steinernema and Heterohabditis species are also recommended for grub control.

Chemical Control

• Both preventative or curative methods of chemical control are effective for grubs. Prevention is best in gardens where grubs are consistently an issue. Treat lawns prior to egg hatching and continue until you see very young grubs. Recommended pesticides for prevention include clothianidin, halofenozide or imidacloprid. Start curative treatment after grubs have started to feed and the young grubs are near the soil surface. This is during late summer to mid fall. Waiting too long allows the grubs to retreat deeper into the ground for winter. Recommended pesticides include trichlorfon.