Ever looked out on your lawn and noticed it’s suddenly become a snack bar for your local birds?
It may be that your yard is infested with African black beetles (also called black lawn beetles). These insects can be a serious problem for your lawn, especially in their larvae stage.
Some lawn types susceptible to beetle attacks include Buffalo, Kikuyu, ryegrass, and fescue. Signs of potential African black beetle infestation include dying patches, yellow or wilted leaves, and grass that’s easy to pull out.
Here are some methods to get rid of African black beetles in your lawn:
- Soap and water
- Natural predators
- Beneficial nematodes
- Pest-attracting plants
- Light traps
- Insecticides
Make sure to practise proper lawn care – a healthy and happy yard is less likely to get bugged down by pest attacks, and will recover better afterwards.
What is an African Black Beetle?
The African black beetle (Heteronychus arator) is an insect that’s native to southern Africa. They’re fairly common in Australia, having been first detected around the 1920s–30s.
African black beetles are considered pests, especially by farmers. The larvae feed on plant roots and can compromise soil structure, while the adults attack a wide range of crops, from wheat to potatoes.
Why are Black Beetles in a Lawn Bad?
Heteronychus arator causes the most damage to lawns in its larvae stage, when it burrows into the soil and begins feeding on plant roots.
Here’s a quick rundown of why these insects can cause lawn problems.
Beetle larvae
African black beetles cause the most damage to your lawn in their larvae stage.
The black lawn beetle begins laying eggs underground in spring (around September). Then the eggs hatch starting late spring in November.
The larvae develop in three life stages (called instars), and will look like grubs, with c-shaped white bodies and orange-brown “heads.” There will be a baggy, greyish section at the rear.
At the first instar stage, the beetles are just 5mm long. They’ll begin to burrow throughout the ground in the second stage, feeding and growing until they fully mature to around 25mm (third stage).
The beetle larvae are most active during these times – around late spring to early summer.
The grub-like larvae eat grass roots and other organic matter. In large numbers, they can destroy your lawn’s root system – leading to bare patches in your lawn or even dying grass.
A larvae infestation can also compromise the soil structure by burrowing holes while looking for food.
Adult beetles
From late summer to early autumn, the larvae become pupae. At this time, they do not feed and are inactive until they emerge as adults.
Adult black beetles emerge mostly throughout autumn. An adult beetle can still cause some damage by eating vegetation, but they’re more of a problem for farmers than they are for homeowners.
The adult black beetle has a lifespan of 8–10 months, and will be mostly dormant through late autumn and winter. They’ll lay eggs in spring before dying.
Adults can fly (they’re better at flying than crawling) and are often attracted to lights at night.
Signs of African Black Beetle Lawn Damage
If you suspect you may have a black beetle problem, there are some signs to look out for.
Inspect both your lawn and your plants – you never know where the infestation might be. And make sure you check regularly, since the earlier you catch the infestation, the better.
Signs of African black beetles in your lawn
For lawns and turfed areas, one of the biggest symptoms is dying patches of grass, especially from November to February.
Other signs to look out for on your lawn include:
- Yellowing or wilted leaves
- Grass that’s easy to pull out
- Small white grubs in disturbed or dug-up soil
- Soil that sinks when stepped on
Many popular types of lawn grass in Australia are susceptible to African black beetle infestations, including:
- Kikuyu
- Buffalo grass
- Couch
- Fescue
- Ryegrass
Australian native grasses tend to be more resistant to pests and easier to maintain. Consider switching grass types to options like kangaroo grass or redgrass.
Signs of African black beetles in garden beds or on plants
For garden beds or other areas in your lawn that have ornamental or edible plants, the symptoms are similar.
Check your plants for signs like:
- Stunted plant growth
- Wilting stems and foliage
- Shredded or frayed shoots and stems
- Ringbarking near the base
- Plants that are easily pulled out
- A chewed-up root system
- Holes in tubers and other underground produce
- Groups of dying plants
How to Get Rid of African Black Beetles
If you do have lawn beetles, don’t panic.
The faster you act, the more effective your treatment will be – and the more likely it is you’ll save your lawn.
Soapy water
The soap and water trick to get rid of lawn beetles works best when applied during spring to summer – when the larvae are most active.
TIP: This trick also works to get rid of lawn grubs!
Soak some hessian or canvas bags in water mixed with some dish detergent, then lay them out on any bare or dying patches.
The larvae will crawl to the surface and attach themselves to the fabric.
You can also simply pour a mix of soap and water onto the ground and wait to see if any larvae or lawn grubs come up to the soil surface.
Mix about 30ml (2 tbsp) of dish detergent in 5L of water, and pour that over 1 square metre of ground.
Dig up the larvae manually and place them in a separate bucket of soap and water to fully kill them off. Drain the mixture, then bag the larvae properly and dispose of them.
Natural beetle predators
If they’re allowable according to your local council laws, backyard hens love a black beetle snack.
Simply keep the surface well-tilled so the larvae or beetles are exposed, giving your chooks an all-you-can-eat buffet.
Alternatively, till the soil regularly and place some low-hanging bird feeders or scatter some bird seed to attract your local wildlife. The birds will turn your lawn into their personal snack bar and leave it beetle-free.
Beneficial nematodes
Here’s a more unique solution – invest in beneficial nematodes.
Specifically, look for the entomopathogenic nematode Heterorhabditis bacteriophora. They occur naturally in eastern Australia but are sold commercially online.
Nematodes are very tiny, worm-like organisms that live in the ground. They only feed on insect pests, leaving grass roots and beneficial insects like ladybugs alone.
Heterorhabditis bacteriophora in particular is most effective against African black beetle larvae.
Nematodes can be a bit pricey, but are an extremely effective organic solution.
For best results, soil temperature should be above 15ºC. The African black beetles should be about halfway through their development – around November to early February.
Water the ground before applying the nematode treatment.
Pest-attracting or repelling plants
This trick works more for the adult black beetles, and keeps them away from your other plants.
Nasturtiums are popular companion plants to attract pests – beetles and other bugs will prefer to snack on the nasturtium instead.
Other prime black beetle targets include eucalyptus seedlings and clover.
On the other hand, you can grow plants that deter insects. These include plants such as garlic, citronella, and tansy.
If you plant in garden beds, turn over the soil every few weeks to check for larvae or adults. You can also try planting a wide variety to mitigate the damage caused.
To prevent egg-laying, plant food crops in midsummer until winter.
Light traps
Again, this works mostly for adults. Much like other insects, adult beetles are attracted to light sources at night.
Deploy a light trap at night to attract the adults. The trap will then either hold the insects until they die or zap them with a light electrical current.
Try the DynaTrap Insect Trap for Pest Control. It comes with a chain for easy hanging and replacement UV bulbs.
Insecticide
This solution is best for a particularly large number of beetles or larvae. Some products are safe enough to apply preventatively, to kill off any eggs in the soil before they hatch.
You can speak to a gardening professional or your local garden centre to ask about the best products to use.
Select insecticides that apply specifically to the black beetle. In particular, look for active ingredients such as chlorantraniliprole (acelepryn) or bifenthrin, which will remain active in the soil for up to six months.
These chemicals provide effective control of the African black beetle and other pests (like Argentine stem weevil larvae and billbug larvae) while leaving beneficial, non-target organisms (like bees and worms) safe.
Some recommended products include Growers Lawn Grub Concentrate, SureFire Fortune Ultra Spray, or Safer Horticultural & Dormant Spray Oil.
For a more natural alternative, you can use HARRIS Cold-Pressed Neem Oil or HARRIS Diatomaceous Earth.
What To Do After Getting Rid of Black Lawn Beetles
Once you’re sure you’ve gotten any infestation or attack under control, it’s time to do some lawn repair.
You may need to top dress and seed your lawn to encourage the growth of new grass in any dead or bare patches.
For larger patches – or if you have Buffalo grass – you’ll have to lay new sod or turf.
Follow proper lawn care such as thorough watering and regular mowing to restore your lawn’s health.
Preventing African Black Beetles in Lawn
There are ways you can protect your lawn or garden from an African black beetle infestation.
These methods aren’t foolproof, but can help deter beetles or minimise their damage.
Strategic planting
Grow a wide variety of plants, and include pest-attracting species like nasturtiums, magnolias, and eucalyptus.
Check for beneficial companion plants if you’re growing crops like potatoes, turnips, carrots, and other underground produce.
Preventative insecticide treatment
You can apply insecticide as a preventative treatment during spring or early summer. This will kill off any eggs or larvae before they can become a problem.
Opt for long-release products like acelepryn which will remain active for months, killing any new eggs or larvae that appear.
Regularly dethatching
Lawn thatch is beneficial in moderation, as the organic material breaks down and returns nutrients to the soil.
However, a heavy build-up of lawn thatch increases the risk of waterlogging, fungal diseases, and pests.
Signs you have too much thatch include spongy ground, unhealthy-looking grass, and the presence of insects such as African black beetles.
To dethatch your lawn, you can use a thatch rake (best for small lawns) or cutting rake (best for bigger lawns). Do this only for warm-season grasses.
Cool-season grasses do not respond well to dethatching or scalping, so opt to rake and aerate your lawn instead.
Regular testing
Keep a close eye on the condition of your lawn or garden plants. If you see any signs of a possible infestation (or any issues at all), don’t hesitate to test the soil surface.
You can either use the soap and water mixture, or dig up a small section of the affected area and check for beetles, lawn grubs, and other problems.
If you’re planning to start a new garden bed or a new lawn, dig down at least 20–30cm deep and check for any eggs, larvae, or pupae.
Proper lawn care
Proper maintenance is one of the best defences against African black beetles in lawn (and other invasive insects).
Mow your lawn regularly – about every 2 weeks during the growing season, and every 3–5 weeks in autumn and winter. Do not cut more than 1/3 the height of grass to keep your lawn healthy.
Water the grass infrequently but thoroughly. This will encourage deeper, stronger roots that are more resistant to insect attacks.
Aerate your lawn at least once a year to improve drainage and prevent soil compaction. Aerating also helps the roots better absorb water and nutrients.
Fertilise your lawn correctly, preferably using a slow-release formula or organic materials (such as compost or mulch).
By keeping your lawn healthy and happy, you’re less likely to get bugged by any pests – or any other problems in your yard!
