There are two main types of lawn grub, each of which can cause devastation to lawns before you are even aware of their presence. Here are some easy ways to recognise and deal with them before they do too much damage.
White curl grub
The first type of lawn grub is the white curl grub. These white, ‘C’-shaped grubs are the larvae of the cockchafer beetle or African black beetle. (Commonly, these grubs are wrongly identified as ‘witchetty grubs’ when observed by home gardeners.) White curl grubs live beneath the soil surface and feed on the healthy roots of grass. Like armyworm, these pests have been known to destroy entire lawn areas completely within a matter of weeks.
How to detect white curl grub
Look for visual signs, such as circular patches in your lawn turning brown or yellow. Your lawn may feel soft and spongy to walk on and you may find grass lying loosely on top of your lawn. (In advanced cases, sections of lawn will be able to be lifted off the surface of the soil like a toupee, as there is no root system left.) For a final confirmation that white curl grubs are present, place a wet hessian bag on your lawn overnight. In the early morning, lift the bag to see if the grubs have come to the surface.
The second type of lawn grub is the armyworm. These army-coloured, khaki- green caterpillars are the larvae of moths of the Noctuidae family. They are a nuisance throughout Queensland and New South Wales and sometimes occur in plague proportions. Armyworm consume the leaves, stems and seed heads of grass. They can decimate entire lawn areas, leaving behind practically nothing but bare earth.
How to detect armyworm
If you notice patches of lawn suddenly dying, this could be evidence of armyworm activity. You may also notice small, grey moths flying around your lawn. (These moths are armyworms in their adult stage, looking for a place to lay their eggs.)
Further signs of lawn grubs
You may see wasps hovering over your lawn. Certain species of wasp are a predator of lawn grubs and use them as hosts to feed their young.
What time of year
Most lawn grub activity occurs in the warmer times of year from early spring, through summer and into autumn.How to Treat Lawn Grubs Lawn Weed Control Chart