Adult false wireworms emerge from the soil during spring and early summer. Eggs are laid singly in moist soil, usually under trash or low-growing weeds. Larvae feed on decaying vegetable matter and newly germinated seeds (e.g. cereals, cotton, soybeans and sunflowers). Both the seeds and growing points are damaged, resulting in patchy stands.
Pterohelaeus spp., Gonocephalum spp.
Larvae are up to 30 mm long, shiny and cream, yellow or tan with three pairs of legs just behind the head. They are hard-bodied, cylindrical and segmented with a rounded head. Adult beetles of Pterohelaeus spp. are 20 mm long and dark grey-black with a distinctive 'pie-dish' shape formed by flanges around the outline of the beetle.
Adult beetles of Gonocephalum spp. are 9 mm long, dark grey-black and often covered in soil. There are flanges around the outline of the thorax (behind the head).
Several species of false wireworms may occur in any particular crop, depending on locality, soil type, organic matter and tillage practices.
Pterohelaeus spp. - eastern false wireworm, striate false wireworm.
Gonocephalum spp. - small false wireworm, southern false wireworm, northern false wireworm.
|Life cycle on maize|
Larvae feed on decaying vegetable matter and crop residues in the soil, as well as on newly germinated seed. They usually have a single generation per year.
Larvae cause most damage to germinating crops during spring while adults are most troublesome in summer.
Larvae feed on germinating seed and chew on seedling roots and shoots, resulting in patchy stands. Adults chew on seedlings at or above ground level, ring-barking or completely cutting the stem.
Use germinating seed baits (GSB) or digging and sieving to detect larvae prior to planting.
Treatment is required if more than 25 wireworm larvae are found in 20 GSB. For adults, apply bait to the whole field if the soil insect rating (SIR) is more than six.
Cultural control: the false wireworm is mainly a pest in areas having heavy, black soils. It prefers cultivated soils rather than zero til. Use press wheels at sowing, which are set at 2-4 kg per cm width after planting rain or 4-8 kg per cm in dry soil.
|Pest status in maize|
Minor, widespread, regular
- Pests of Field Crops and Pastures: Identification and Control Editor: P.T. Bailey