So you’ve spent all spring carefully tending your lawn, watering it and spreading new seed. It is finally looking lush, green and healthy. Time to sit back and relax, right?
But now you’re noticing brown patches and your grass is starting to look bald. What is going on? Why is your healthy lawn looking yellow and patchy even though you’re spending hours caring for it?
The answer could be Japanese Beetles. These pests are a gardener’s nemesis and can badly affect your lawn as well as a host of garden plants. Since they arrived in 1916, the insects have been chewing their way through gardens and causing devastation.
They are the number one pests for grass and can be a frustrating and difficult problem to deal with.
That’s why we’ve put together this how-to guide so you can destroy these beetles once and for all. Just follow these simple steps and you can get these tiny bugs out of your garden and give your plants a chance to thrive.
What are Japanese Beetles?
Japanese Beetles, often referred to as lawn or white grubs, are the larva stage of beetles and are a widespread pest. The white, C-shaped creatures lay beneath your soil and feed on grass roots.
Grubs will grow into mature beetles which will then mate and lay eggs – creating more grubs.
They can spread quickly. An adult Japanese Beetle has a short life span of around 30 to 45 days but females can lay eggs every 24 hours which means you might find them spreading rapidly through your garden.
How do you know you have beetles in your lawn?
There are a few key signs that beetles have taken up residence in your backyard. Spotting these signs early means you can get on top of the problem before they breed and spread.
- As the lawn turns greener in spring, you should look for brown patches. The brown patches are caused as the grubs eat the roots of the grass. If you see a brown patch, you can verify if it was a grub that caused the damage very simply. Take a knife and cut a small amount of the patch up. Lift the turf and if it can roll up easily then there are no roots to the grass and the grubs have been there
- If you are watering your lawn well but still seeing brown patches then grubs could be the cause. In late summer have a thorough inspection of your lawn and mark out any brown patches.
- Seeing more wildlife in your garden can also be a telltale sign. Birds, skunks, armadillos, raccoons or moles all love the beetle grubs and will travel to find them. If you’re suddenly noticing these creatures around and they’re digging up your lawn, you’ve probably got beetles. Just double check using the above method as they can sometimes just be digging for worms
- If your grass feels spongy then this can also mean you have Japanese Beetles present. In a well-watered lawn, a spongy feel to your grass can be a sign that beetles are living below.
- Look at your neighbour’s gardens. If the yard next door has grubs they can move into yours.
What conditions do they need to thrive?
Adult Japanese Beetles like the warmth and they feed and mate in clear, warm weather. You might see the beetles creeping about on plants at about mid-morning on sunny days and by mid-afternoon, you will see the peak number of beetles arrive.
Beetles also need lots of moisture to keep eggs safe and brand new grubs damp and healthy. This is why a sprinkler system while keeping your lawn watered can also increase the risk of getting a Japanese Beetle infestation.
You can particularly see this at golf courses which often have automatic irrigation systems.
How to get rid of Japanese Beetles
1. Shake them off plants
One of the best ways to get rid of mature beetles is to manually remove them. This can be time-consuming but it is a good way to make sure you are removing all of them.
Choose the time when most beetles are active, around mid-afternoon, then lay out sheets below plants with the beetles on. Shake the plants and the beetles will fall onto the ground sheets where you can remove them.
2. Pheromone traps
As the adult beetles start to come out from the soil, in May to July, you can use pheromone traps to stop them getting onto your property. This is particularly important if your next door neighbour has a beetle problem.
Put these traps around the perimeter of your property to stop the grubs or beetles getting in.
3. Floating row cover
A floating row cover can also be used as a physical barrier to stop beetles getting onto the plants.
These products allow sunlight, water and air in but keep the bugs out. This way you can protect your plants and cut off the food supply to the beetles in your garden.
4. Spread nematodes on lawns
Nematodes are tiny parasites that love nothing more than hunting and killing beetle grubs in your soil. Add some mulch to your lawn containing nematodes and then let nature take its course.
5. Use milky spore
This is a bacterium that also destroys grubs living in the soil. You can use it to spread across your lawn in the summer or fall but you cannot use this method when the ground is frozen.
6. Use kaolin clay to create a barrier
Clay is a thick impenetrable barrier that grubs cannot live in. By putting a layer of clay soil over your lawn or flowerbeds, you can prevent pests from living on the ground.
The downside to this method is that water does not hold in clay soil and you may find your plants drying out over time.
7. Insecticide spray
Use a specialised insecticide to kill off these bugs if you already have an infestation. The spray is non-toxic to honey bees so you can use it without worrying about harming other creatures.
8. Botanical pesticides
You should water in pesticides after you’ve applied. Watering moves the pesticide itself down into the soil and encourages grubs to move upwards to get to the water.
So if you’ve been wondering why your lawn is brown and your grass looks like it is dying, check your backyard for beetles. Whether you have fully grown adults or just the harmful grubs, these are a pest you want to get rid of fast.
Follow this step by step guide and you will rid your garden of this annoying resident once and for all.
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