A Grass grub infestation can be devastating to lawns leaving an aftermath of brown and yellow patches across the lawn. The best way to tell if you have grass grub damaging your lawn is to dig up a patch of turf and flip it over. When the grass grubs are doing the most damage they should be visible among the roots of your lawn. They will look like a 25mm white/creamy C shape with a brown head above six legs. A sign you have pests in the lawn is lots of bird activity.
To control the infestation a chemical control is advised. Females lay eggs shortly after they emerge from hibernation in spring. Therefore if you leave an infestation untreated you or your neighbour are more likely to have a problem next season. We recommend using Kiwicares Lawnguard Granules applied February – May. Applications outside of this time frame will be less effective as the grass grub will be too deep in the soil for the product to reach.
We always say that chemical controls should be a last resort, however there are no reliable organic controls. So if you want to avoid applying strong chemicals and damaging your soil life then prevention is what you need. Keep the lawn healthy by aerating and topdressing once a year and fertilize with organic options like blood and bone. Grass grub thrive in moist conditions so water less frequently but for longer, this will encourage a stronger root system that can manage a little nibbling. Raising the height on your mower for spring will also discourage females trying to lay eggs and will also encourage deeper roots.
Encourage predators, which are mainly birds like starlings and blackbirds. These floor feeding birds appreciate fruit and mealworms on a floor feeder. However blackbirds are most attracted by leaf litter that they can turn over searching for insects and gardens with low shrubs and trees. Starlings are attracted to places with large trees that have enough space to hold a colony, although this can get a little noisy. Another predator of grass grub are said to be wasps which are usually attracted to woody plants and leaf litter.
Once you have controlled your infestation of grass grub you will need to resow any patches in either autumn or spring when the temperature is around 10 degrees celsius. Make sure to give the lawn a good rake first removing all the dead grass, this will also ‘fluff up’ the soil a little making germination easier. To save time it’s a good idea to also spray lawn weeds a few weeks before reseeding patches.