Beneficial Insects

Reducing chemical use by encouraging beneficial and predatory insects.

Part of living an organic lifestyle is about learning not to rely on chemicals as a means of protecting ourselves and our crops from pests. Pests such as caterpillars, aphids and scale can ruin crops, but by encouraging beneficial insects, birds and small creatures such as frogs and lizards, we can attain a balance.

Pests become a nuisance because they are often fast breeding and quickly take advantage of an out of balance system. They can be a sign that soil-life is not optimal and that plants may be weak and stressed.
 They also provide an ample supply of easy-to-catch food for many small creatures. Spiders, wasps, frogs, lizards and birds all benefit from infestations of what we call pests and they call dinner.

Insect pests tend to come in flushes. When this happens the temptation is to spray but if you allow the infestation to continue a little longer, the appropriate beneficial insects will usually come along and clean-up for you. More established suburbs will have a better variety of good bugs, especially if there are plenty of trees and vegetable gardens around.

The longer it is since poisonous chemicals were used the more diversity and more beneficial insects there will be in your garden. Hopefully the neighbours don’t spray either, as spray drift can affect your garden too. New gardens tend to get a lot of pests to start with but after a few years with no highly toxic sprays there should be a good selection of good guys in your garden.
 Once the balance is established there’s much less worry about other things eating your veges.


Better Known Beneficial Insects.


Ladybird beetles and their larvae eat aphids, mealy bugs, mites, thrips, moth eggs and other small pests. They can multiply rapidly given the opportunity (ie an aphid colony to eat). Yellow clusters of eggs appear on the host plants and before long the little spiny-looking black-and-white larvae are hatched and growing fast on a feast of aphids.



Dragonflies eat mosquito larva during their larval stage, which is spent in water and is best survived with no hungry, large-mouthed goldfish. As adults, a large variety of flying insects are caught in flight, a fine skill indeed.



Lacewings are pretty little brown or green insects with big eyes. The eggs are tiny and laid at the end of a tiny pedestal to stop the newly hatched lacewings eating each other or being predated upon by ants. The lacewing larvae then feast on aphids or other tiny insect eggs they find.


Brown lacewing on an everlasting flower.


Hoverfly larvae attack aphids, mites, scale and young caterpillars. The adults are attracted to gardens by flowers such as Allysum, St Anne’s lace, tansy, yarrow and many others. The adults of these “good bugs” all need flowers for pollen and or nectar so it is important to have a good supply of flowers.


Parasitoid Wasps

Wasps bear a resemblance to ants, to which they are related. They are smaller, skinnier and more elongated than paper wasps, generally, and some are very small, indeed.

  • Aphelinid wasps – these are tiny and lay their eggs inside aphids. They can sometimes be seen in a busy aphid colony.
  • Trichogramma wasps – parasitise many kinds of moth eggs, by laying their eggs inside them. These are very small and very helpful.
  • Paper wasps and mud daubers put spiders and caterpillars in with their larva before sealing them in for the larvae to eat when they hatch.
  • Chalcid wasps – very, very small and very sensitive to pesticides. They attack scale, flies, aphids, leafhoppers, whitefly, beetles, mealy bugs and caterpillars.
  • Ichneumonid wasps – these are great killers of caterpillars, even able with its long ovipositor (egg-laying tube) to put eggs into a caterpillar that is within a tree’s bark. Their action prevents many caterpillars from reaching maturity.
  • Braconid wasps – attack caterpillars by laying eggs on or inside them. They can be small insects and 100 or more grubs can be found inside one caterpillar. Once emerged the grubs make a cocoon nearby to finish their metamorphosis. Limp, empty looking caterpillars are a good sign that you have parasitic wasps in your garden.

Parasitoid Flies

Tachinid flies look quite similar to house or blow flies, but more stout and usually more hairy. Tachinid flies attack larvae of many insects and are economically significant in protecting organic crops.

For more information about Tachinids 

So you see, fly spray doesn’t just kill flies, it might kill your vegies too, if you accidentally poison your beneficial insects.

Happy insect-watching! And follow Beneficial Insects on Facebook for more helpful tips and information.

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