How to Control Tasmanian Grass Grubs

Tasmanian grass grubs can do extensive damage to lawns, ornamental plants and trees, consuming all their foliage and blooms. Implementing control measures at the first sign of trouble is critical. Altering the biological development of the grubs is the most-effective way to rid yourself of the pests. Long-acting products on the market made from a bacteria deadly to the grubs and adult beetles are your best and safest bet, among some ancillary strategies. An additional way to cope is to attract birds to the area that eat the grubs. A mass planting of feverfew, which the grubs and beetles do not like, might also work. Grubs are a nuisance that can be difficult to deal with, but a combination of strategies should yield a reprieve from their destruction.

Biodynamic treatment to control grubs, such as Ballance Bioshield

Feverfew plants

Heavy compression roller

Apply a biodynamic agent to the soil. This agent will introduce a bacteria that will consume grubs and beetles. Dig holes in the affected soil during the early fall months, roughly 1-to-3 inches deep. Pour the granules into the holes. You need to deposit roughly 60 lbs. of the granules in holes for every 2 1/2 acres of grass, lawn, pasture, etc.

Cover over each hole with soil so that the bacteria is not exposed to ultraviolet light that can kill it. When the infected grubs die off, the still-active bacteria is released back into the soil, continuing to infect grubs for up to 5 years.

Rent a heavy metal drum roller similar to those used for compacting soils and gravel. Make repeated runs over your lawn, aiming to crush as many adult beetles as you can. This is a no-chemical, low-cost alternative treatment and will create a break in the infestation and give your lawns and plants some relief.

Attract birds to the area with the plants and the trees they like. Keep seed and fresh water available. Birds eat grubs and the mature beetles so increasing their presence in your yard may help control the infestation of lawn grubs.

Create a mass planting of feverfew in and around infested areas. Tasmanian grass grubs and beetles do not like feverfew, and this may act as yet another layer of low-impact deterrence and biological control.

Insecticides that contain Fenitrothion are effective in killing Tasmanian grub larvae and mature beetles. It is also extremely toxic to humans and animals. It is almost immediately deadly to fish when it is washed into or seeps into water supplies. If inhaled or absorbed through your skin, it can cause nervous system and reproductive system damage and skin irritation. Biodynamic products and physical killing of the beetles should be attempted first to protect both you and the wildlife.