It is hard to get out in the garden these days without applying chemicals to get rid of pests we don’t want. As in life, most gardeners will be on the lookout for those insects that are a problem (I have never met anyone that likes mosquitoes) – they eat our veggies or favourite flowers but are we sometimes going for overkill and taking out the good bugs too. Who are they good guys and equally who are the bad guys?
So how do we know the difference? And what we can do about them?
THE GOOD GUYS
The only insect able to turn its head and look over its shoulder, praying mantis’ lie in wait for unsuspecting insects before snapping them up in their strong forelegs. They are useful for controlling flies, mosquitoes, caterpillars, aphids and grasshoppers.
Tip: Set any pruned branches with praying mantis egg cases aside in a sheltered spot.
What would we do without bees? Bees transfer pollen from flower to flower, enabling them to form fruit. There are 1500 species of native bees in Australia, 10 of them stingless.
Tip: Nectar-rich flowering plants will attract bees. Native bees love Angophora and Eucalyptus trees, Brachyscome groundcovers, grevilleas, Leptospermum and Westringia.
They may not all be beautiful but learning to love these efficient eight-legged predators will help your garden thrive. Huntsman spiders are among the most beneficial group of spiders; they capture and feast on cockroaches, moths and flies but are harmless to humans.
Tip: Leave spider webs and egg cases alone. Wear gloves while gardening to avoid bites.
When the sun goes down, these carnivorous predators emerge from rocks, logs and underground to hunt insects and their larvae, the pesky cabbageworm in particular. There are thousands of species within the ground beetle family, but most have flattened bodies, long legs for moving fast, and prominent mandibles.
Tip: Clover attracts ground beetles.
These familiar bugs feast on such garden nasties as mealybugs, aphids and spider mites. Orange or red with black spots, ladybirds live on or under leaves and a single adult can consume more than 5000 aphids during its lifetime.
Tip: Attract ladybirds with plenty of nectar and pollen-producing plants.
Worms not only aerate and nourish your soil when they turn dead plant matter into nutrient-rich worm castings, they also attract birds that can further help keep pests at bay.
Tip: Keep garden soil moist and mulched. Consider starting a worm farm (which use red worm or tiger worm species) that makes use of your kitchen scraps.
THE BAD GUYS
Caterpillars are the larvae of moths and butterflies, and have voracious appetites – they can defoliate an entire tomato plant in just a few days. Some, such as looper caterpillars, feed under leaves and lie along stems so can be hard to spot and control.
Tip: Herbs such as rosemary, mint, dill and thyme all repel caterpillars.
Aphids are so small that if you do manage to spot them, the damage has probably already been done. These pear-shaped bugs suck plant leaves dry until the leaves curl up and fall off, and can also spread plant diseases.
Tip: Mix warm water with garlic and powdered cayenne pepper. Leave in the sun for a few days, strain and spray onto affected leaves.
These sapsuckers weaken host plants by removing their food supply. Scale insects are about 2-3 mm long and produce a sticky substance called honeydew, a food source for sooty moulds. The resulting red, brown or black coating reduces a plant’s ability to photosynthesise and looks unsightly.
Tip: Apply pure eucalyptus oil to affected leaves.
Cabbage white butterfly
This butterfly’s babies are bad news for your veggie patch. Its caterpillars favour cabbages, cauliflower, broccoli, celery and beetroot. Adult female moths have white wings and a black spot on each forewing.
Tip: Plant plenty of rosemary, mint, dill, sage, garlic, thyme, oregano and chamomile throughout your garden to deter them.
Mites are closely related to spiders and most have four sets of legs. These tiny arachnids puncture plants with their fangs and suck up the juice. Infested plants have silvery mottling and their leaves and stems end up covered with webbing.
Tip: Keep outdoor plants well watered and spray indoor plants regularly with a mist of water – mites thrive in dry conditions.
Adult thrips feed in the blossoms of fruit trees, vegetables and ornamental garden plants, causing blossoms to turn brown and fall off, and preventing fruit from setting. Hatched offspring feed on flowers alongside their parents.
Tip: Apply pyrethrum (made from chrysanthemum blossoms) on affected plants and keep them well watered.
Slugs and snails
Silvery trails leading to large holes in leaves are telltale signs that these culprits call your garden home. Slugs and snails feed mostly at night and some can live for 12 years.
Tip: Handpick and drown in soapy water rather than stepping on them (their eggs may still hatch). Create barriers around plants with crushed eggshells or sawdust.
These hard-workers are attracted to the honeydew excreted by pests such as aphids, scale and mealybugs. Uncontrolled, ants can spread these insects throughout your garden by shifting their eggs onto fresh, new growth.
Tip: Paint a 6 cm-wide band of horticultural glue (made from natural gum resins, vegetable oil and wax) on stems and trunks. Other deterrents are mint and garlic.
Flies, fleas and mosquitoes
These nuisances can drive humans (and their pets) to distraction. Fortunately, there are several natural solutions.
Tip: Fight fleas with tansy, pennyroyal, spearmint and fennel; deter flies with basil, mint, rue and tansy; repel mosquitoes with garlic, tansy and pennyroyal, and plant sassafras near windows and doors. Ward off fruit fly with basil and tansy plants.