Amazing Australian garden spiders that perform natural pest control
Spiders are one of your garden's primary pest management systems, operating year round for free, with no chemical residue and more precision than anything you can buy.
A garden orb weaver at the centre of its web, one of the most productive nocturnal pest controllers in the Australian garden.
Australia has approximately 10,000 spider species, more than the total spider fauna of most other countries. They occupy every layer of the garden, hunt by every method available and target insects that cause problems including aphids, fungus gnats, whitefly, caterpillars, mites, leafhoppers, thrips and more.
Aphids on the underside of a leaf — exactly the kind of pest that small web-building spiders target most readily.
They have been doing this for around 380 million years, which gives them a considerable head start on systemic pesticides.
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How much do spiders actually eat?
the numbers are extraordinary
A 2017 study by Swiss researchers Martin Nyffeler and Klaus Birkhofer calculated that the world's spider population consumes between 400 and 800 million tonnes of insects and other prey every year. To put that in context, the total weight of all humans on earth is around 287 million tonnes.
A St Andrew's Cross spider with prey — a single spider of this size can catch hundreds of insects per week.
Studies in agricultural settings have found that spider populations in crop systems can suppress pest insect numbers by 50 to 80 per cent during peak activity periods.
what they actually eat
The pest species that most affect Australian gardens are the ones that spiders target most readily. Small web-building spiders capture fungus gnats and aphids. Larger orb weavers catch moths and beetles. Ground-hunting wolf spiders pursue soil-dwelling larvae. Crab spiders intercept the insects visiting your plants from above. The coverage is three-dimensional and continuous.
The fastest way to reduce your spider population
Pesticides do not distinguish between pest insects and the spiders that eat them. A single spray event can eliminate the local spider population for a season, removing the very system that was suppressing the pest in the first place. The pest population then rebounds, often faster than the spider population recovers, because its predators are gone.
Web-building spiders
Web-building spiders are capable of catching hundreds of insects per week depending on their size. The silk itself is stronger by weight than steel, elastic enough to absorb the impact of a flying insect without breaking and rebuilt from scratch with regularity.
An orb web threaded through a callistemon at dawn — anchor points in dense shrubs are prime web-building territory.
St Andrew's Cross Spider (Argiope keyserlingi)
The St Andrew's Cross spider has white zigzag bands woven through the centre of its web in an X pattern. These bands are called the stabilimentum. Researchers have considered several explanations for this: the bands may make the web visible to birds and prevent them flying through it, they may reflect ultraviolet light to attract insects, or they may help camouflage the spider.
St Andrew's Cross spider (Argiope keyserlingi) — the zigzag stabilimentum is one of the most studied and least understood structures in the spider world.
The males are so much smaller than the female that they were initially described as a different species entirely. A male approaching a female web for mating taps the silk in a specific pattern before advancing and often retreats rapidly after mating to avoid being eaten.
Garden Orb Weaver (Eriophora transmarina)
The garden orb weaver is responsible for the large, circular webs that appear between fence posts, across doorways and among shrubs, then disappear by morning. The spider dismantles and eats its web every day at dawn, recycling the protein in the silk before rebuilding. A full orb web, up to 60 centimetres in diameter, is constructed in under an hour.
Golden orb weaver (Nephila) — the golden silk of this species is strong enough to catch small birds, though insects are the intended prey.
The spider hangs at the centre of the web, front legs resting on signal threads that transmit vibrations from any point on the structure. When an insect hits, it responds within a fraction of a second, moving to the point of impact and wrapping the prey in silk before biting. The web is also engineered with a break pattern, a series of radial threads that give way at a certain load, allowing large insects to bounce free rather than destroy the whole structure.
Leaf-Curling Spider (Phonognatha graeffei)
The leaf-curling spider builds a conventional orb web with one distinctive addition: it finds a dead leaf, curls it into a cone shape using silk and suspends it at the centre of the web as a retreat. The spider sits inside the cone with its front legs resting on signal threads and emerges when prey arrives.
Leaf-curling spider (Phonognatha graeffei) inside its characteristic curled-leaf retreat at the centre of the web.
If the spider needs to move to a new location, it carries the leaf retreat with it. If no suitable dead leaf is available nearby, it will travel some distance to find one before building its web.
Ambush and active hunters
Ambush and active hunters rely on stillness, camouflage and speed, positioning themselves where insects will come to them or pursuing prey across foliage surfaces. They are among the most specialised predators in the garden.
A jumping spider in position — active hunters stalk their prey with a deliberate, cat-like approach before striking.
Australian Crab Spider (Thomisus spectabilis)
The crab spider sits motionless on flowers — daisies, tea trees, pittosporum — and waits. Visiting insects do not detect it until they are within striking range, at which point the spider seizes them and injects venom that causes rapid paralysis. It regularly catches insects far larger than itself, including native bees, hoverflies and wasps.
Australian crab spider (Thomisus spectabilis) — the white colouring is not fixed; this spider can shift to pale yellow over several days to match a different flower.
The crab spider can change colour from white to pale yellow over several days to match a different flower. This is an active physiological process and the result is one of the most effective ambush systems in the garden.
Lynx Spider (Oxyopes species)
Lynx spiders are fast, visually acute hunters that pursue prey across leaf surfaces. They have eight eyes arranged to provide near-360-degree vision and are named for their ability to leap onto prey from a standing start.
Lynx spider (Oxyopes species) — eight eyes arranged for near-360-degree vision make this one of the most visually acute hunters in the garden.
They are particularly effective against small flying insects that move through the foliage layer and are too mobile for web-building spiders to catch reliably.
Jumping Spider (family Salticidae)
Australia has around 70 described jumping spider species and they are among the most visually capable hunters in the garden. Their two large forward-facing eyes give them depth perception that is exceptional for an invertebrate. They can also see into the ultraviolet spectrum, which influences how they assess prey.
Jumping spider (family Salticidae) — the large forward-facing eyes give these spiders depth perception that is extraordinary for an invertebrate of their size.
Jumping spiders are active in full daylight and prefer warm, sunny surfaces. They are bold and curious, often turning to observe the observer, and are completely harmless. Their hunting behaviour is complex enough that they have been used in research into invertebrate problem-solving and spatial reasoning.
Ground hunters
Below the visible surface of the garden, in the leaf litter, mulch, soil and around the bases of plants, a separate community of spiders operates. Ground hunters patrol the ground layer continuously, hunting the insects and soil-dwelling larvae that live there.
A huntsman spider — fast, flat-bodied and completely harmless, these ground and bark hunters are among the most effective large insect predators in the Australian garden.
Wolf Spider (Lycosa species)
Wolf spiders are large, fast, ground-dwelling hunters found in the leaf litter and mulch of almost every Australian garden. They hunt by pursuit, using two large forward-facing eyes that provide excellent depth perception to track and run down prey across open ground.
Wolf spider (Lycosa species) — females carry their spiderlings on their back for several weeks after hatching, often transporting fifty or more offspring simultaneously.
Wolf spiders also have a reflective layer behind the eyes called a tapetum lucidum, the same structure responsible for eyeshine in cats. Shine a torch at a garden bed at night and the wolf spiders present will show as small green or orange points of light in the leaf litter, a practical way to assess the spider density of your garden.
Trapdoor Spider (Missulena, Idiosoma and related genera)
Trapdoor spiders excavate a burrow in the soil and construct a hinged door at the entrance from silk, soil and plant material, fitted so precisely it is nearly invisible when closed. The spider waits just inside with its front legs resting against the door, detecting ground vibrations from passing insects. When prey moves within range, it opens the door, seizes the insect and retreats in less than a tenth of a second.
Trapdoor spider at its burrow entrance — the hinged door is engineered from silk, soil and plant material and can be held shut from the inside against considerable resistance.
Trapdoor spiders are extraordinarily long-lived for invertebrates. The oldest spider ever recorded was a trapdoor spider from Western Australia, a female from a long-term ecological study that lived to 43 years old before being killed by a parasitic wasp.
Spider silk
Spiders produce up to seven different types of silk from different glands, each with different properties: dragline silk for structural framework, capture silk for sticky spirals, silk for egg sacs, silk for wrapping prey and silk for attachment points.
How to attract more spiders to your garden
go chemical-free
This is the single most important step. Broad-spectrum insecticides, including many products marketed as safe or organic, kill spiders directly or eliminate their prey base. A garden without insects has no spiders, and a garden without spiders has no biological pest control. The two populations are inseparable.
keep the ground layer undisturbed
The ground layer of a garden, including leaf litter, mulch, fallen bark and undisturbed soil, is the primary habitat for wolf spiders, trapdoor spiders and dozens of other ground-hunting species. Leave sections undisturbed and resist the urge to remove all debris from garden beds.
Leaf litter supports far more life than a raked garden bed — ground-hunting spiders, beetles, moths and their larvae all depend on an undisturbed ground layer.
plant in layers
Dense groundcovers, native grasses and layered shrub plantings create the structural complexity that supports diverse spider communities. Web-building spiders need anchor points. Ambush hunters need foliage surfaces. Ground hunters need covered ground. A garden planted in layers supports all three groups simultaneously.
A layered native garden provides anchor points for web builders, foliage surfaces for active hunters and covered ground for the species working below.
leave webs where they are
A web across a path is easily ducked under. The spider that built it has invested significant energy in its location and will rebuild repeatedly if disturbed. An old web with debris in it is not a sign of neglect. It is a sign of a functioning spider that has been feeding successfully in that spot. The debris is the remains of pest insects.
A note on spider identification and risk
The spiders described in this article are all common, non-aggressive species that pose no meaningful risk to humans going about normal garden activity.
Redback spider (Latrodectus hasselti) — favours dry, sheltered spots such as under pot rims, in rockery gaps and in garden furniture. Easily identified and to be avoided.
However, the redback spider (Latrodectus hasselti) and the funnel-web spider (Atrax robustus and related species) are the two species that warrant genuine caution. Redbacks favour dry, sheltered spots such as under pot rims, in rockery gaps and in garden furniture.
Funnel-webs are found in moist, sheltered soil in eastern Australia and produce a distinctive collar of silk around their burrow entrance. Checking under pots before picking them up and wearing gloves when reaching into dense ground cover is sensible practice.
keep reading
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How to plan, plant and care for a thriving native garden, whatever your experience level.
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