Caterpillars are the larvae of moths and butterflies of the order Lepidoptera. There are more than 20,000 species which occur in Australia, but only half have been scientifically named. Only about 400 of these species are butterflies – the rest are moths. That means there are almost as many species of moths in Australia as there are native plant species.
Moths and butterflies usually have proboscises to suck nectar from flowers, while their larvae have chewing mouthparts. The larvae of pest species can inflict considerable damage to plants. Luckily not all caterpillars are pests. Out of the thousands of caterpillars out there, only about 50 can be considered pests.
Australian tree ferns are elegant plants that can add a lush, tropical feel to any garden. However these stately plants can fall victim to infestations of voracious caterpillars that chew on the fronds and detract from their beauty. Getting rid of caterpillars on australian tree ferns requires persistence and an integrated pest management approach, but with the right techniques you can protect your plants.
Identifying Caterpillars on Tree Ferns
The first step is learning to identify the pests. Tree fern caterpillars may include:
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Loopers – Slender green caterpillars with white stripes that make looping movements as they crawl. They chew irregular holes in foliage.
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Cutworms – Plump soft-bodied caterpillars that hide at the base of plants during the day. They chew through stems and fronds at night.
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Armyworms – Tan or dark caterpillars with white and orange stripes. They skeletonize leaves by devouring tissue between veins.
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Bagworms – Caterpillars that build spindle-shaped bags on plants in which to feed and pupate. They eat holes in leaves.
Watch for chewed fronds, excrement, and visible caterpillars to identify an infestation. Thoroughly inspect the tops and bottoms of all fronds.
Remove Caterpillars by Handpicking
Handpicking caterpillars is an effective organic method. Wear gloves and pluck any pests you find off of the tree fern. Drop them into soapy water or seal them in a plastic bag to kill them. Check plants daily and remove all life stages from eggs to adults before they damage the plant.
Apply Neem Oil Sprays
Spray Neem Oil Neem oil sprays kill small insect pests, like caterpillars and mites, by suffocation. It is a botanical extract made from the oil of Neem tree seeds. Neem oil is safe and will not harm humans or pets.
To use neem oil, mix it with water according to label directions. Spray all surfaces of tree fern fronds, including the undersides. Reapply weekly until you see no further signs of caterpillars. Neem oil also repels some insects to provide protection.
Use Bacillus Thuringiensis
Bacillus thuringiensis (Bt) is a natural bacterium that specifically kills caterpillars that ingest it, while causing no harm to people, wildlife, or plants. When caterpillars eat leaves sprayed with Bt, they die a few days later.
Purchase Bt formulated for caterpillars and mix according to label instructions. Completely coat tree fern fronds to control infestations. Make repeat applications 7-10 days apart until caterpillar activity stops. This biological insecticide works well when combined with neem oil sprays.
Apply Horticultural Oils
Horticultural oils smother soft-bodied insects like caterpillars on contact. They also help deter some pests from infesting plants. For tree ferns, stick to a lightweight mineral oil and test on a small area first.
To use horticultural oil, add a few drops of dish soap and mix the oil with water according to label rates. Spray on a calm day to thoroughly cover fronds, including the undersides. Reapply every 7-10 days for 2-3 weeks to kill newly hatched caterpillars.
Use Pheromone Traps
For armyworms, bagworms, cutworms, and loopers, pheromone traps can capture adult moths before they lay eggs on your tree ferns. The traps contain sex pheromones that lure specific moth species inside.
Place traps near infested plants in early spring and check weekly. Replace lures monthly. Traps alone don’t provide full control, but they reduce mating and supplement other methods.
Apply Diatomaceous Earth
Diatomaceous earth (DE) is a natural silica dust that abrades the cuticles of insects, causing dehydration. Sprinkle food grade DE on tree fern fronds, avoiding the crown. Reapply after rain or heavy watering. DE is safe for plants and people, but kills bees, so avoid dusting nearby flowers.
Use Beneficial Insects
Encourage natural predators like ladybugs, lacewings, parasitic wasps, and predatory stink bugs in your garden. They feed on tree fern pests while causing no damage. Plant small flowering plants nearby to attract and provide food sources for beneficial insects. You can also purchase some predators to release.
Practice Prevention
Good cultural practices go a long way towards preventing caterpillars on tree ferns:
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Keep ferns healthy with proper water, light, and fertilization to withstand and recover from pest damage.
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Remove any dead or dying fronds which attract pests.
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Clear plant debris from around tree ferns to eliminate hiding spots for caterpillars.
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Use row covers on smaller tree ferns to create a physical barrier against pests.
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Rotate chemical treatments to help prevent resistance.
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Introduce biological controls early before pests get out of hand.
By taking an integrated approach and using multiple methods together, you can effectively control tree fern caterpillars without resorting to harmful pesticides. Always check new plants for caterpillars before bringing them home. Maintain vigilance and be prepared to take action at the first signs of damage to keep your Australian tree ferns caterpillar-free.
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Best Treatment for Caterpillars
The first thing you need to do when you see caterpillars on a plant is identify them. If its a serious pest species, you may need to control the caterpillars, if it is not a pest species you may be able to tolerate the damage. For example, you might tolerate a few caterpillars of the Orchard Swallowtail (Papilio aegus) feeding on the leaves of your Lemon tree, so that you can enjoy the beautiful butterflies later. You might tolerate the massive and colourful caterpillars of the Emperor Gum Moth (Opodiphthera eucalypti) feeding on a young Gum Tree, so that you can boost the declining numbers of their iconic adult moths.
There are plenty of ways to combat pest caterpillars. The secret to pest control is to keep an eye on your plants, so that you can detect pest caterpillars early. After a while you will become familiar with what caterpillar damage looks like (see Symptoms of Caterpillar Damage). If you find damage, you should have a closer look to see if you can find some caterpillars and work out what they are.
If you routinely get incursions of pest caterpillars, there are several things you can do to prevent serious damage (see How to Prevent Caterpillars Appearing).
Regular monitoring of your garden will ensure that a major infestation of Caterpillars doesnt occur overnight. All treatments are way more effective if you can catch an infestation in its early stages.
To treat, try Yates Natures Way Caterpillar Killer- Dipel. The product is based on naturally occurring bacteria (Bacillus thuringiensis) which acts as a stomach poison against caterpillars. The product will only affect caterpillars, so your good bugs are safe. Follow the label directions and it will work against caterpillars in your garden.
Yates 750ml RTU Advanced Garden Insect Killer
Yates 15kg Dynamic Lifter Organic Plant Food & Soil Improver Pellets
What are Caterpillars & How to Get Rid of Them
Caterpillars are the larvae of moths or butterflies of the insect order Lepidoptera. Caterpillars are incredibly diverse in their anatomical forms, their feeding habits and their behaviour. Caterpillars have various common names depending on the species involved – for example, Inchworm, Armyworm, Woolly Bear, Looper, and Cutworm.
The caterpillar stage is the only time that moths and butterflies grow. When caterpillars first hatch from an egg, they are tiny (approximately 1 mm long), but to grow larger the caterpillars need to moult. As a caterpillar feeds, it expands, and the skin stretches and eventually splits. After emerging from the split skin, the now larger caterpillar is usually pale in colour for a few hours, until its new skin hardens and resumes its usual colour. Each growth stage is known as an instar and there are always several instars before pupation. Once an adult moth or butterfly emerges from a pupa it does not grow.
Depending on the Lepidoptera species involved, caterpillars may feed on any part of a plant – flowers, leaves, bark, stems, fruit, trunk or roots. They may feed openly during the day, or only feed at night, or they may feed out of sight by tunnelling into various plant parts. The thing to note about pest species of caterpillars, is that they eat 90% of the food they will ever eat in the final instar of their larval stage. If you have pest caterpillars in your garden, it is best to control them at an early instar, therefore, when they are small.
Moths and butterflies form the order Lepidoptera, a word which means lepís scale + pterón wing, therefore, scaly wings. The wings of moths and butterflies are covered with tiny overlapping scales, as are the head and parts of the thorax and abdomen.
The scales give the insects their colour, either through the pigments contained in the scales or by structural colouration (such as diffraction). Scales also provide insulation, which has allowed moths to become the dominant night flying insect.
Moths and butterflies have a proboscis, which they use to extract nectar from flowers. When not in use, the proboscis curls up neatly under their heads.
In the insect world there are always oddities. There are wingless moths (such as female Case Moths), and some moths dont have proboscises and dont feed at all (such as Emperor Gum Moths).
What is the Difference Between a Moth and a Butterfly?
Butterflies always have antennae with a club at the tip, while moths usually have feathery or thread-like antennae. Butterflies usually hold their wings upright when resting, unless they are sunning themselves, while moths usually fold theirs down.
Do Moths Only Fly at Night?
No, some species such as the Grapevine Moth, aka Vine Moth (Phalaenoides glycinae) are day-flying moths. Grapevine Moths are black moths with yellow or white wing markings with a wingspan of about 50 mm. They have tufts of bright orange hairs on the tip of their abdomen and at the base of their legs. Males and females are not easy to tell apart unless you examine the tip of their abdomen – it is squarish in males and tapered in females. Grapevine Moth is found in south-eastern Australia including SE Queensland, New South Wales, Victoria, Tasmania and South Australia.
Most caterpillars (larvae) usually take the form of an elongated fleshy tube with legs. Caterpillars have three pairs of thoracic legs, which are located just behind the head. They also have a varying number of fleshy barrel-shaped abdominal legs or prolegs. These prolegs are very useful for gripping a stem while feeding. Most caterpillars have four pairs of prolegs, but Looper caterpillars have only two pairs which results in a characteristic looping gait.
The head of caterpillars is dominated by what look like two huge eyes but is actually the epicranium or head capsule of the caterpillar. The head capsule is divided by an inverted Y-shaped line extending down from the top of the head. This Y-shaped line distinguishes caterpillars from any other insect larva – for example, Beetle or Sawfly.
Caterpillars have simple eyes (known as stemmata) which are only capable of distinguishing between dark and light, giving the caterpillars some spatial awareness. Caterpillars have six stemmata, which are inconspicuous raised dots, located on each side of the head capsule.
When caterpillars moult, they usually eat their old skin, but discard the old hardened head capsule. Larvae of the Gum-leaf Skeletoniser Moth (Uraba lugens) keep their old head capsule and stack it on top of the new one. After a few moults, the caterpillars have conspicuous pointy hats. These caterpillars are great favourites of children who call them haterpillars.
The Gum-leaf Skeletoniser caterpillar is also very hairy, and those hairs can irritate the skin of some people. Mature Grapevine Moth (Phalaenoides glycinae) larvae are mostly smooth and fleshy with a few hairs. Grapevine Moth larvae are conspicuous black-and-white patterned caterpillars up to 50 mm in length, with a pink hump and small pink markings on the sides.
Moths and butterflies grow through a life cycle of complete metamorphosis – egg, larva, pupa adult. Depending on the species involved, female moths or butterflies may lay their eggs on or into plant tissue, and they may lay eggs singly or in batches.
Grapevine Moth has a typical life cycle. Eggs are laid on stems and leaves and hatching larvae develop through six larval instars. Final instar larvae leave the food plant and wander for a couple of days before pupating in a silk lined cell in the ground or cracks in vine wood or fence posts. There can be as many as three generations per year depending on the climate.
Control Catepillars In The Garden Organically And Effectively
FAQ
How to get rid of caterpillars on ferns?
How do I stop caterpillars from eating my tree leaves?
How do I get rid of caterpillars without killing my plants?
How do you get rid of caterpillars in Australia?
Australian gardeners swear by using the horticultural molasses (available at garden supply centers) and dish soap method as a way to get rid of caterpillars. As a bonus, it also deters fire ants. Caterpillars become butterflies, but they can also do damage in the garden.
Can you kill caterpillars with pepper spray?
Pepper spray: You can kill caterpillars with fresh peppers. Wear gloves and eye protection and finely chop enough habanero peppers to fill 1/2 cup. Crush six garlic cloves. Puree the peppers and garlic with 2 cups of water, 1 tablespoon of vegetable oil, and 1 teaspoon of dish soap in the blender.
Can Caterpillars attack ferns?
Ferns are popular garden shade plants, adding a wild and sometimes tropical appearance to the landscape. Various types of caterpillars can attack ferns, some doing quite a lot of damage. Plucking them off by hand is the first solution to try, and it may be enough for some types of caterpillars.
How do I get rid of caterpillars in my garden?
To treat, try Yates Nature’s Way Caterpillar Killer- Dipel. The product is based on naturally occurring bacteria ( Bacillus thuringiensis) which acts as a stomach poison against caterpillars. The product will only affect caterpillars, so your ‘good bugs’ are safe. Follow the label directions and it will work against caterpillars in your garden.