Troubleshooting
Lawn Grubs
- Have you ever wondered why your lovely green lawn suddenly goes brown and straw like?
- Are there moths and wasp-like insects flying over your lawn?
- Maybe the leaves on the grass runners are just disappearing?
If this is the case, you may have lawn grubs.
What are Lawn Grubs?
Lawn Grubs are leaf eating caterpillars, and there are three main types:
Armyworm
These caterpillars are dark green, smooth and hairless, 25 to 30mm long with distinctive stripes along the side of their body, feeding at night through the growing season. They feed voraciously on the grass blades attacking on various fronts like soldiers (hence the name Armyworm), sometimes devastating the entire lawn.
Sod Webworm
This particular grub is greyish to tan in colour, about 20mm long and spotted, also feeding at night through the warmer months. The adult moth drops her eggs at random during the night, eggs hatch in one week, usually chewing off leaves near the base of the sheath.
Cutworms
Thick bodied caterpillars with a length of 38 to 50mm. These caterpillars are greenish grey, brown or black often with spots or stripes. Feeding at night through the growing season, they can chew the grass shoots down to the surface but are normally considered a minor problem.
The grubs generally hatch in the summer and early autumn. They are a seasonal problem as the moths lay their eggs through the warmer months. The intensity and time of first appearance can be greatly influenced by how cold our winter has been.
How do I know they are there?
There are several quick ways for early detection.
- Circular to irregular patches of your lawn dying or thinning.
- Place a wet hessian bag on your lawn overnight, the grubs present will be visible when you lift the bag in the morning.
- An accumulation of small green pellets of excrement (similar to balls of grass mulch) found within the thatch of damaged areas.
- A reddish-purple wasp type insect hovering around the surface of your lawn. These wasps are often mistaken as the cause of Lawn Grub, but in fact they are actively seeking out the Lawn Grub so they can inject the caterpillar with it's own eggs, using the grub as a host.
How do I fix the problem?
The only sure way is to spray an insecticide. When using insecticides ensure the manufacturer's instructions are followed.
How often do I have to treat my lawn?
Simply because you have eliminated an infestation does not mean the insect will not reappear. This is due to the fact that you have only eliminated the moths larvae, not the moth, who can lay more generations.
We suggest that during the months (October- April) applications should be applied immediately to your lawn, once damage is observed. A follow up application 5-7 days after is highly recommended to overcome the infestation. Water in after each application with the equivalent of 6-12mm rainfall.
After treating for Lawn Grub, a simple application of fertiliser will help shoot and leaf growth. Then continue to water and mow as normal.
