The hungry caterpillar is a cute book character, but a nuisance for many gardeners.
Butterflies and moths are great pollinators and important to your local ecosystem, but as caterpillars, they can be pretty destructive.
A caterpillar infestation can quickly eat up vegetables, orchards, and other plants – ruining months of hard work.
Some key signs of caterpillar damage include leaves with holes or scalloped edges, defoliation, and tiny pepper-like frass (their poop).
How to get rid of caterpillars in your garden? Try one of these solutions:
- Manual removal
- Destroying nests
- Attracting beneficial insects
- Attracting birds
- Applying neem products
- Using biological pest control
- Mixing homemade pepper spray
- Applying insecticides
You can also prevent them from eating your plants with DIY deterrents, companion plants, or netting.
Keep your crops safe so they don’t become a larvae buffet. Grub your gardening tools and get ready for some caterpillar control.
About Caterpillars
Caterpillars are larvae – specifically, they’re the larval stage of either moths or butterflies, in the Lepidoptera order.
There are over 20,000 species of moths and butterflies in Australia, but don’t freak out! Only about 50 types of caterpillars are categorised as pests.
Those types of insect larvae are considered harmful since they can eat garden plants and crops, often leaving devastating results.
Common Types of Caterpillars in Australia
It’s essential to identify the types of caterpillars you have in your garden, because not all of them are pests.
Talk to your local garden centre or any gardening group to learn what types are fine to ignore.
Some common pest caterpillars in gardens in Australia include:
- Armyworms – green with white and brown stripes
- Box caterpillars – green with black stripes
- Cabbage moth caterpillars – yellow or brown with green
- Cabbage white butterfly caterpillars – striped green caterpillars with black markings
- Cinnabar caterpillars – black and orange stripes
- Cluster caterpillars – greenish to purple-brown, with triangular spots
- Corn earworms – green, pink, or brown with visible hairs
- Cutworms – greyish or brown, curling into a C-shape
- Diamondback caterpillars – light brown, then later on bright green
- Egg fruit caterpillars – creamy white, later becoming pinkish
- Lily caterpillars – black with yellow and/or white lengthwise stripes
- Looper caterpillars – green, and move by curling into a horseshoe then stretching
- Tent caterpillars – bright markings (orange, white, blue) with silky, tent-like nests
What Causes Caterpillars in Your Garden?
You get caterpillars in your garden when adult moths or butterflies lay eggs on plants.
These eggs can come as a cluster or as a singular egg, and are typically white or yellow. You’ll usually find them on the underside of leaves or flowers, or along branches.
An adult moth or butterfly can start laying eggs from spring to early autumn. The eggs hatch in just a few days, after which the larvae – aka the caterpillars – emerge.
After emerging, the caterpillars begin eating to grow bigger. Caterpillar activity in Australia is highest from spring to late summer, when they feed intensely.
The next stage of the life cycle is pupating, where the caterpillars surround themselves with a silk-lined cell. The adult insects emerge after several weeks.
Signs of a Caterpillar Infestation
A few caterpillars here and there won’t be cause for too much concern. They could even be beneficial, providing food for local birds, beetles, ladybirds, and spiders.
Too many of these pests, however, can cause some serious damage.
Common signs of caterpillar damage in your garden include:
- Holes in leaves
- Scalloped leaf edges
- Skeletonised leaves
- Nests (usually web-like)
- Defoliation (loss of leaves)
- Empty egg clusters under leaves
- Frass (caterpillar poop, which looks like little pepper grains)
Particularly susceptible plants include brassicas, potatoes, beans, peas, cabbages and other leafy vegetables.
Check garden beds and crops regularly for any signs of an infestation.
How to Get Rid of Caterpillars in Your Garden
If you already have a pest problem on your hands, there are several solutions.
Here are some of the best methods for controlling caterpillars in your garden. They’ll work on most species, from green caterpillars to hairy caterpillars.
Remove them manually
If you don’t have too many caterpillars to deal with, you can simply do some picking!
Fill a bucket halfway with hot water and a few tablespoons of dish soap. Wear rubber gloves and steel your stomach.
Settle down in the section of your garden with infested plants. Begin thoroughly checking for caterpillars – especially underneath leaves.
Pick off each caterpillar and drop it into the bucket, where it will drown. Keep working until you’ve removed as many caterpillars as you’re able.
For non-pest caterpillars, place them in a cardboard box. You can bring them to a wild meadow or roadside area away from residential spaces.
Destroy caterpillar nests
This is a more proactive approach, but it’s most effective if you spot caterpillar nests before the eggs hatch. However, you can still attack a nest when caterpillars have emerged.
Look under leaves or along branches for nests, which usually look web-like and are made of silk.
Take a sharpened stick, trowel, or similar garden tool and scrape or pierce the nest. Collect the nest remains and any inhabitants, then dump them in a bucket of warm soapy water.
The best time to attack caterpillar nests is early in the morning or late at night. This ensures that most caterpillars are in the nest instead of out having a snack.
Attract insects with plants or seeds
You can check online or in gardening centres for special seed mixes that attract beneficial insects. Many of those garden guests will be natural caterpillar predators.
Insects such as parasitic wasps, ladybirds, and lacewings all eat caterpillars (plus other small insect pests).
Alternatively, grow some insect-attracting plants (or “host plants”) alongside your crops! Some popular options include coriander, dill, fennel, and yarrow.
You can consult a professional gardener about which plants to grow and the best way to position them.
Attract birds
Birds are also natural predators of caterpillars (and lawn grubs).
Set up some low-hanging bird feeders or scatter some bird seed near your vulnerable plants. Alternatively, grow flowering natives like flowering gums, dwarf grevilleas, and paperbark.
After that, simply sit back and wait for your garden to turn into a bird buffet.
You can also check your local council regulations if they allow you to keep backyard chooks. However, check the type of caterpillars first – some can be toxic to chickens! (Usually, it’s the hairy ones.)
Apply neem products
Neem is a botanical extract and is one of the most popular organic insecticides. It’s commonly available as neem oil, although other places sell it as a powder.
Neem oil works thanks to its active ingredient, azadirachtin. When caterpillars eat plants treated with neem, the compound stunts their maturity, which leads to them dying off.
Many gardeners use neem as an insecticide and fungicide since it’s non-toxic to humans and animals (unless ingested in large amounts).
Try HARRIS Neem Oil Concentrate or PLANC Neem Cake.
Use biological pest control
One of the most effective methods for controlling caterpillars is a naturally-occurring soil bacteria, Bacillus thuringiensis (Bt).
The bacteria works by destroying the stomach lining of caterpillars after they’ve eaten any treated plants. Check your local garden centre for products that contain Bacillus thuringiensis, which comes in powder or liquid form.
Best of all, this bacteria is perfectly safe for your plants and other insects, since it’s toxic only to caterpillars and other plant-eating worms.
Another form of biological control is the use of beneficial nematodes, especially Steinernema carpocapsae. The nematodes enter caterpillar bodies then infect them, causing them to die.
Use homemade caterpillar solutions
You can mix up some DIY pepper spray to treat caterpillars on your plants. It’s a great way to get rid of caterpillars naturally.
Be careful when preparing this – wear gloves and eye protection while working.
Finely chop enough habañero peppers to make up 1/2 cup, then crush about six garlic cloves. Put these in a blender or food processor with 2 cups of water, 1 tbsp vegetable oil, and a bit of dish detergent.
If you can’t get habañeros, you can substitute them with jalapeños. What you’re after is capsaicin, the spicy compound that irritates most animals and insects.
Blend the ingredients until they form a puree, then transfer the mixture to a sealed glass jar. Leave it somewhere sunny for 2 days, then strain the solution into a spray bottle. (A coffee filter works great!)
Alternatively, simmer 1–2 tbsp of cayenne pepper or chilli flakes in 1 litre of water for 15 minutes. Stir every few minutes, keeping the pot partially covered in between to minimise the steam stinging your eyes.
Transfer the solution to a glass jar and let it sit for 24 hours to further infuse the capsaicin. Strain the solution into a spray bottle and add 2 tsp of dish detergent or castile soap.
Test the mixture on a small leaf first to ensure the plants won’t get damaged. If everything’s fine, spray the solution directly to get rid of caterpillars.
Work early in the morning or late at night so the spray doesn’t scorch the leaves!
Apply insect sprays
If nothing else works, or if the infestation is too large, you can use a commercial systemic insecticide.
Some effective products include Summit Caterpillar and Webworm Control or Safer Caterpillar Killer Concentrate. Both are advertised to be safe around vegetable patches and other organic gardens.
Avoid spraying these products on flowers, as they could harm bees and other pollinating insects.
How to Stop Caterpillars From Eating Your Plants
Prevention is better than cure, and there are several ways to prevent caterpillars from damaging your garden.
Trim off infested leaves or branches
If you’ve spotted an egg cluster on a leaf or branch, cut it off before the eggs can hatch.
This will still work even if the larvae have already emerged, as long as they aren’t too large or numerous.
DIY caterpillar deterrent
You can mix up some homemade solutions to repel caterpillars. This will keep them away from any plants you want to protect.
Try one of these homemade caterpillar repellants:
- 1 litre of warm water, 1 tbsp horticultural molasses, and a bit of dish soap
- 1 litre of water, 3 crushed garlic cloves, 1 tbsp vegetable oil, and 1 tsp dish soap
- 1 litre of water, 2 tsp neem oil, and 1 tsp dish detergent
- 3 litres of water and 2 tbsp white vinegar
Spray your chosen solution on any vulnerable plants. You can test it on a small leaf first to ensure it won’t cause damage.
Some gardeners also try lining the base of their plants with cardboard or tin foil. These prevent caterpillars from crawling up the plant and reaching their food sources.
Moth deterrents
You can deter non-beneficial insects from your garden to prevent eggs from being laid. Avoid having lights around your crops and plants at night – or set up moth-attracting lights away from the areas you want to protect.
Another easy way to protect your crops and other plants is by covering them with garden netting or horticultural fleece.
This will prevent moths and butterflies from gaining access to lay eggs on the leaves and branches.
Companion planting
Some strong-smelling herbs and crops will repel caterpillars from your yard. Some good choices include lavender, sage, garlic, and dill.
Do not plant mint directly into the ground, as it spreads quickly and becomes highly invasive.
Alternatively, do the opposite of companion planting – grow your crops away from butterfly-attracting plants. That lessens the chances of them laying eggs on your crops.
FAQS about Caterpillar Control
Have any other questions about controlling a caterpillar infestation? Here are some common things people ask.
Should I kill caterpillars in my garden?
Yes – if they’re a pest species. Some types of caterpillars will grow into beneficial insects that you’ll want to have in your yard.
However, if your garden is showing signs of serious caterpillar damage, though, you may need to kill them off.
Will vinegar stop caterpillars?
Yes – but with a caveat. Vinegar is highly acidic, and it can alter the pH and destroy beneficial microbes in the soil.
If you’re opting for a vinegar solution, make sure it’s heavily diluted. Do not use vinegar as a long-term solution for pests or weeds.
What is the best spray for caterpillars?
Homemade pepper spray is one of the most effective and organic ways to treat caterpillars in gardens.
Another great option is a mixture of horticultural molasses and dish detergent.
How do I get rid of caterpillars permanently?
There’s no singular foolproof way to get rid of caterpillars permanently. You can do your best to prevent non-beneficial species of moths or butterflies from laying their eggs on your plants, but nothing is 100% effective.
Good gardening habits and vigilance for signs of caterpillar damage can help you prevent an infestation. Paired with caterpillar deterrents, you’ll have the best weapons to keep your garden plants happy and safe.
