LAWN GRUBS

20 January 2021

This page will help you to identify various types of pests and provide some advice on how to easily manage them yourself.

There are three types of lawn grub that eat the leaf of lawns in South East Queensland, these are; Army Worm, Sod Web Worm and Cut Worm, these are all larvae of small moths that are active from spring to autumn but more common in the wetter months from December to May. Lawn grubs prefer healthy, lush turfgrass, so be on guard during this time. 

These small moths seek out the lushest lawn and lay their eggs in flight (Sod webworm) under building eves, underneath the leaves of plants, shrubs, trees and within the turf canopy. Hundreds of microscopic larvae drift on fine threads onto the ground, the ones that land on a lawn develop into grubs feeding on the leaves of the turf plant. If hatching occurs when no wind is present, a heavy outbreak could occur and in an isolated area, this could cause complete defoliation within days. Under severe infestations, the stems of some grasses are sometimes eaten as well. The average life cycle of most lawn grubs during periods of activity is usually around three weeks. A healthy lawn will easily recover from a mild outbreak of grubs however newly established lawns left unchecked can be completely destroyed in severe outbreaks, especially on Blue Couch varieties. 

There are other pests that live in the soil and eat the roots causing unhealthy turfgrass growth. The main pest we see in SE Qld is the Black Beetle larvae. Low populations will generally not be noticeable, however, heavy infestations can cause turfgrass loss. It is difficult to diagnose as the larvae are not visible unless you expose the soil. 

 We have a new pest soon to arrive in South East Queensland.

The “Fall Army Worm” is migrating down the Queensland coast from Asia. This pest looks similar to our regular Army Worm only it is larger and more ferocious. We are yet to see the effects of this pest, but we have been advised that “Acelepryn” offers protection. 

Do you have lawn grubs and how can you check? 

• Check the lawn in the early evening for the presence of this small white moth. Sometimes walking around the lawn will cause them to fly away, 
• Another indicator is the presence of a small red wasp which flies low over the grass during the day, the wasp is searching the lawn for a host grub to lay its eggs into, 
• Another method to check for the presence of lawn grubs is to lay out a wet hessian sack or a large wet rag over the suspected areas in the evening, check under the sack in the morning and the grubs should still be active in the dark cool environment, by thinking it is still nighttime. 

What can you do? 

• For total peace of mind apply the preventive product “Acelepryn GR” in spring/ early summer to prevent infestations for up to 6 months. Acelepryn is non-toxic and safe to use. Its easily applied as a granule through a normal fertiliser spreader and provides protection for all lawn grubs including Black Beetle larvae. 

• For a quick kill, the chemical “Bifenthrin” seems to be the most available chemical available. This product can be used as a protective treatment when applied at regular intervals or as a knockdown treatment to control existing pests. Lawn grubs generally feed at night, so for best results apply pesticide in the late afternoon or as indicated on the label. BEWARE! A new outbreak can occur within one to two weeks of spraying, if there is a lot of lawn grub activity in your area you could expect another re-infestation after the chemical has been used up.  

BEFORE YOU APPLY ANY PESTICIDE (HERBICIDE, INSECTICIDE OR FUNGICIDE) READ THE LABEL, FOLLOW THE DIRECTIONS AND BE AWARE OF SAFETY PRECAUTIONS AND FIRST AID 

We stock these products at our Tamborine office. Alternatively, you can order online from Lawn Solutions Australia.

How can you prevent it from happening? 

• • Apply the preventative herbicide “Acelepryn” at the start of the lawn grub season. Up to 6 months of control can be achieved at a higher rate. Acelepryn is also effective at preventing Black Beetle when applied in spring. 
• • Bug lights are quite effective. They won’t stop the larvae from dropping in and causing some damage, but they will help catch the moths laying eggs in the area and causing major outbreaks, 
• • Do not overfeed your lawn with high nitrogen fertilizers during the summer months, alternatively use organic fertilisers and seaweed-based products that strengthen the turf plant making it less desirable for grubs to eat, 
• • Keep an eye on lawn areas being defoliated and do the overnight sack test as mentioned earlier. Treat as soon as grubs have been identified. 

As always, if you have any more questions please don’t hesitate to contact us for free expert advice on 1800ALLTURF or 07 5543 8304.