Spodoptera, Herpetogramma & Agrotis spp.

Other common names:

Armyworm, sod webworm and cutworm.

Description:

The 3 common "lawn grubs" found in Australia include Armyworm, sod webworm and cutworms. These "lawn grubs" are the caterpillar or larvae stage of an adult moth which attack the turf canopy (leaves). The commonly appear in spring through to late summer. The moths lay their eggs in flight (sod webworm) or within the turf canopy or structures such as eves (armyworm) being covered in scales, which appear to be light gresish in colour.

Too many times people think the early symptoms of a lawn grub problem are a dry patch or even a disease outbreak. After identification and initial control, it is necessary to show caution about ongoing attacks. Lawn grubs prefer healthy, lush turfgrass, so be vigil during their active seasons.

• Armyworm: Armyworm (Spodoptera mauritia) are green in colour and change to dark green as they feed and grow. They have distinct light coloured lines down the sides of their bodies. Armyworm live in the thatch layer of the turf and feed (largely) at night. They have the ability to strip and eat the grass blades moving on a front when populations are high (hence the name Armyworm), causing devastating loss of turf plant material, resulting in straw like appearance being left behind. Lifecycle: Adult moth lays a large amount of eggs, within 2 to 5 days they become larvae (or grubs), then within 18 to 24 days they become pupae for 5 to 8 days when then become a moth. The cycle then continues unless broken.
• Sod Webworm: Sod webworms (Herpetogramma licarsisalis) may be green, brown or grey. Most have dark circular spots. They live in silk-lined tunnels and chew grass off close to the crown.
• Cutworm: Cutworms (Agrotis spp.) greenish grey, black or brown in colour with spots or stripes.

Control options:

• Pesticides: See available tabs below for registered products. As lawn grub feed at night, for best control apply pesticide in the late afternoon. Use as per label instructions.
• Integrated Pest Management (IPM):
  • Place a wet hessian bag on the turfgrass overnight and check early morning to see if grubs are visible. Bird activity (feeding) is also a strong sign of activity.
  • There are a number of wasp (e.g. red predatory wasp) and fly parasitoids that successfully control low populations of lawn grubs.
  • An entomopathogenic nematode (EN) Steinenema carpocapsae is available commercially for use in turf in Australia.  This species is an effective biological control agent against armyworm, when treatments are correctly administered.
  • Cane toads are also efficient in providing a form of biological control when lawn grub are in low populations.
  • Guinea fowl (not chickens) which prefer to eat bugs and pests, including lawn grub.
  • Use a combination of approaches listed on this page.
• Cultural: Avoid using excessive nitrogen fertilisers and opt to use slow release turf fertilisers.
• Mechanical: Reduce thatch levels reducing favourable feeding and living conditions.

Disclaimer:

Turf Finder or its developer accepts with no responsibility for any consequences whatsoever resulting from the use of any information or product(s) listed herein. Products are to be applied as per label instructions.