Good vs. Bad Bugs in Your Garden
The Good, the Bad, and the Bugly (or How to Hire an Assassin)
To help give our plants the best chance to survive and thrive, it is essential to initiate some form of pest control in our gardens. The best way to do this is not by resorting to deadly sprays and poisons which will destroy Mother Nature's carefully designed ecosystem, but by simply learning who eats whom.
To do this, we divide our garden predators into two simple categories—good bugs and bad bugs. Bad bugs include all those creatures who like to munch on our prized fruit and vegetables and favourite flowering plants. Most of these bugs have, at various stages of their development, other natural predators. These are the ones we call the good bugs. (I will use the term 'bugs' here more widely than to just refer to insects. I will also include spiders, lizards, frogs, bats, birds, and fish.)
We might wonder: "If the bad bugs' main purpose is to eat all our fruit and vegetables and destroy our crops, why did God create them?" Well, everything does have a purpose. It's just that the purpose may be at odds with our priorities. For instance, in spring, when birds are busy feeding their newly hatched chicks, nature supplies them with a smorgasbord of emerging grubs and caterpillars. It isn't God or Nature's fault that those bugs' preferred food source is found in our vegetable garden.
That being said, it's not wrong for us to help nature take its course and encourage and attract the good bugs to our garden to feast on their natural prey. In this article, you may have to turn your concept of good and bad upside down because the creatures we employ to exterminate others are the ones we call the good bugs, and their victims are the bad bugs.
Here is a list of many of the bad bugs that you may find in your garden. (Please note that I am based in Australia so the list of bugs I include here may or may not correspond with what is found in gardens in other parts of the world.) I am sure, though, that insect species are probably more widespread than other animal species which often tend to be exclusive to certain countries or regions. (The book by Jessica Waliser discusses bugs more specific to North America, along with great photos, and I recommend it to my Northern Hemisphere friends.) I will provide additional details with some of these, others I will just provide the name. Good Bug, Bad Bug
- Ants can be both bad and good bugs. Their farming of aphids can leave the plant covered in unsightly black bubbles or spots and can eventually shorten the life of the plant. I also found that ants seemed to infest and spoil the calixes of rosella plants I was growing, but whether this was also the result of aphid infestation I'm not sure.
- Aphids gather in pale green clusters at the tips of new growth. They suck the soft green stems, leaves, and buds of plants such as citrus, roses, hibiscus, gardenia and hydrangea. Ants farm them for milk, and a trail of black ants on a plant usually leads to aphids.
- Apple Worm
- Bean Beetle
- Borers or Termites attack wattle and older trees. A tell-tale sign is a split in the bark surrounded by white sawdust.
- Cabbage Moth/Butterfly is a small yellowish coloured butterfly which lay its eggs on cabbages, broccoli or cauliflower, on which the larvae then feeds.
- Cane Toads are a pest even though they eat huge quantities of insects. They have an insatiable appetite and also prey on native frogs, lizards, good bugs, your dog and cat's food, and poison many native wildlife and water supplies.
- Carrot Fly
- Click Beetles and Wire Worms. Wire worms are the destructive root eating larval stage of the click beetles that children love to play with.
- Cockroaches breed like crazy in bark and wood chip mulch, so never use those. It is much better to use high-grade lucern or hay mulch instead. Trying to poison them will kill good bugs too. chickens and guinea fowl can help keep them under control.
- Codling Moth and Fruit Fly lay their eggs in your eagerly awaited fruit just before they are ripe enough to pick.
- Cucumber Beetle
- Cut Worms live just under the soil surface, ready to munch on seedlings as soon as you plant them.
- Earwigs sleep in a high dry place during the day, then dine at night, so they are hard to find. They especially love eating dahlias and hollyhocks.
- Grasshoppers can decimate your garden if left unchecked, though adults hate water so a good hosing will get them moving. If you attract birds to your garden they will have a feast on them.
- Harlequin Bug
- Hornworm Caterpillars "What's big, fat, and green, with bright markings and a spiked tail?" "A hornworm caterpillar, that's what!" These are voracious eaters and hard to see among the leaves.
- Ladybirds (Ladybugs) with 26 and 28 spots only. These are hungry plant eaters so are classified as bad bugs, whereas all the other varieties are insectivorous and therefore good bugs.
- Lawn Grubs cause the brown patches in the lawn from winter to mid-summer. They thrive in long dry spells and emerge as the African Black Beetle. they dislike wet soil so a constantly watered lawn will leave them to rot and die.
- Leaf Miners are too small to see but evidence of their activity is a lacy white pattern on the leaves of plants. They eat the flesh between the upper and lower skin of the leaf.
- Mealy Bugs look like fluffy white dust on the stems of plants. They are partial to the lower stems of canes, palms and house plants.
- Mosquitoes will seek out any water receptacles or ponds in which to lay their larvae, so turn all buckets, wheelbarrows, etc. upside down so they can't gather water when it rains.
- Slaters are flat and grey and look a little like tiny armadillos. They will also quickly demolish your seedlings.
- Slugs and Snails are night feeders that, because they move on slime, prefer a damp, shady environment. They often congregate under the shady lip of a plant pot, in empty pots or on the side of bricks.
Beneficial Insects (Bennies)
One of the "in" words among today's pest management specialists, "bennie," short for beneficial—those good bug predators and parasitoids that help your garden thrive.
Employing Deadly Assassins in Your Garden
There are literally thousands of willing workers that will freely assist with pest management and many other jobs in your garden if you just supply their needs. Natural pest management is not about substituting organic pesticides for chemical ones. Organic sprays can chase away or kill beneficial insects as well as the pests and should be used as a last resort.
We need to utilise a range of smart strategies to ensure a balanced ecosystem is created so that for every bug that wants to eat your plants, there are six or seven others that want to eat it or its larvae.
Let's take a look at some of the highly efficient assassins available for hire to bump off the enemies of your garden.
Good Bugs and Other Hired Assassins
- Ants can be both good or bad bugs. They are the self-appointed garbage collectors or funeral directors of your garden, clearing away the dead bodies and shells of other unfortunate creatures. However, their liking for harvesting aphids and their invasiveness can make them a pest.
- Assassin Bugs are efficient killers that use their large proboscis to stab, paralyze and kill their prey such as caterpillars, grasshoppers, and green vegetable bugs. They then inject a powerful enzyme which liquefies their prey's internal organs so they can drink them.
- Bats: small insectivorous bats fly around at night, sometimes devouring over 500 insects an hour.
- Bees: even though they aren't predators, both the honey bee and small native bee are essential to every garden, feeding in pollen and nectar and helping to pollinate our precious plants and flowers.
- Beetles: although some are pests, many others such as ground beetles and bombardier beetles are great assets in our garden. They prey as larvae and adults on such things as caterpillars, cutworms, march flies, nematodes, fruit fly larvae, slugs, snails, thrips, aphids, ant, termites and grasshopper eggs.
- Birds: small birds like fantails, flycatchers, robins, wrens, and willy wagtails are welcome visitors to the garden as they eat a wide variety of pests. it is good to plant some native shrubs with small spiky leaves to provide them with nesting sites safe from larger birds.
- Butterflies, though their caterpillar larvae are partial to making a meal of some of our plants, the adult butterflies make up for it by helping to pollinate and beautify our garden by their presence.
- Centipedes, which are not often warmly welcomed in the garden due to their potentially nasty sting, nevertheless are good assassins who love to dine on slugs.
- Dobson Fly: although the adult flies are vegetarians, the larvae are aquatic and large amounts of mosquito larvae.
- Dragonflies and Damselflies, as adults, deftly catch flies, mosquitoes, and other flying insects in the air, while their larvae live in the water and hungrily devour mosquito wrigglers. A small garden pond is a good investment to encourage these effective workers to move in.
- Frogs can also be lured by a pond and are efficient assassins of many pests including moths, cockroaches, flies, and grasshoppers.
- Hoverflies are one of the most valuable of the good bugs to have in your garden. These clever flies imitate bees and wasps to avoid being attacked as they hover over plants waiting for prey like aphids, beetles, and caterpillars. They lay their eggs in aphids so their offspring have a plentiful food supply when they hatch. Hoverflies also need nectar and pollen, so like bees, help to pollinate the plants in your garden.
- Lacewings: the beautiful iridescent adults fly around at night feeding on pollen and honeydew, while their hungry larvae feed on aphids, mealy bugs, mites, scale, thrip eggs, and white fly. They are so helpful as aphid controllers that they are produced commercially and sold to greenhouses and to the agricultural industry.
- Ladybirds (ladybugs) are one of our most important allies at keeping aphids under control. They come in many colours and spots, but make sure you identify the bad 26 and 28 spot varieties as they are notorious plant munchers.
- Lizards are valuable to the garden as they eat a wide range of insect pests. The most common type found in suburban gardens are usually skinks and geckos which appreciate shelter such as rocks and logs as protection from birds and cats.
- Praying Mantises: both the adults and larvae eat a wide range of smaller insects including the cabbage moth. In fact the often lay in wait to pounce on the predators of the lower pests when they move in for the kill. their presence is a good indicator of a balanced ecosystem.
- Robber Flies: these relatively large flies catch pests on the wing and, like the assassin bug, inject their prey with an enzyme so that they can drink the insides.
- Snakes. Now I know snakes are not welcome in many gardens, but they are often a valuable asset in larger market gardens and farms, especially where things like sugar cane, corn, or bananas are gown as they control the mice and rat population. Generally, if you treat them with respect and give them a wide berth, they can work for you in return. Most snakes will die if they eat a cane toad, except for the harmless keelback snake which seems to be able to eat young toads with no ill effect.
- Spiders are very highly evolved creatures and probably the most important predators and assassins of all. The problem is that most humans are afraid of them so they don't get much good publicity. If it wasn't for them we may not even be here because the Earth may be run by insects.
- Wasps and Mini-Wasps are almost all useful predators or parasitoids, attacking a wide range of pests. Some wasp larvae live either in or on the bodies of their hosts such as caterpillar larvae. Many adult wasps feed on open flowers and nectar and pollen.
Bad Bug Repelling Plants
tansy, spearmint, pennyroyal
nasturtiums, chives, tobacco
marigolds, onions, potatoes, turnips, white geraniums
onion, radish, turnips
garlic, larkspur, rue
balm of gilead, fleabane, lavender, santolina
rosemary (dried), santolina
French lavender, marigolds, mustard
Jerusalem artichoke, radish
marigolds, nasturtiums, tobacco
marigolds, nasturtiums, rhubarb
Good Bug Attracting Plants
ground and bombadier beetles
Anise, Celery (in flower), Dandelion, Marguerite daisy
Chamomile, Chervil, Hyssop, Marigold, Mint
ground beetles, woolly apple aphid parasites
diamondback moth larvae
wide variety of parasites
oriental fruit moth larvae, strawberry leaf bugs
many beneficial insects
oriental fruit moth larvae
Companion planting to disguise the shape and smell of your veggies and attract and distract various bugs also helps, as does creating healthy soil by mulching, composting, and crop rotation. The healthier your plants are, the more resistant they will be to attack by pests and disease.
For more detailed information on companion planting see my other article, "Companion Planting (Good and Bad Neighbours)".
The Permaculture Home Gardener by Linda Woodrow
Intimate Secrets of a Flamboyant Gardener by Babs Corbett
Companion Gardening in Australia by Judith Collins
Paradise in Your Garden by Jenny Allen
This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.
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© 2014 John Hansen