Organic gardeners don’t garden alone: we have a host of helpers. Some of these are the insects and other organisms that live off our garden insect pests. We refer to this as biological control or, more simply, natural pest control.
“Biological control is the beneficial action of parasites, pathogens, and predators in managing pests and their damage. Biocontrol provided by these living organisms, collectively called ‘natural enemies,’ is especially important for reducing the numbers of pest insects and mites”.(1) The more balanced this interaction is, the more effective.
Biological control, or natural pest control, is what Nature uses when human beings don’t interfereBiological control, or natural pest control, is what Nature uses when human beings don’t interfere Click To Tweet
Natural Garden Pest Control
The most numerous natural garden helpers are insects that feed, breed and thrive in the garden. For this reason, organic gardeners don’t pull out a can or spray pump full of insecticide whenever we see a garden pest – we like our beneficial insects to be well fed.
Insects perform three main functions in the garden: they act as (1) pollinators, (2) predators or (3) parasites. The pollinators help plants to produce seeds or fruit while predators and parasites deal with the pests that would otherwise damage your crops.
Attracting beneficial bugs to our gardens contributes towards the creation of a balanced ecosystem there. Click To Tweet An organic gardener aims to achieve this and has no need for expensive and often toxic pesticides.
Some Beneficial Insects
Ladybird (ladybug, lady beetle) – The ladybird is a small colourful beetle with colonies worldwide. Mostly their colour is red with black spots but other colours, including orange and yellow can be found. The ladybird and its larvae are voracious eaters of many garden pests including aphids, mealy bugs and spider mites.
Bumblebees – Bumblebees are much bigger than honey bees and of a different species. Their size and their hairy bodies enable them to collect and deposit large quantities of pollen, making them excellent pollinators.
Ground Beetles – belong to a large family worldwide. They are usually dark brown to black in colour. With their powerful jaws, they will attack almost any insect pest on the soil surface.
Dragonflies – are usually seen around garden ponds or they fly over from nearby streams. Their food consists mainly of mosquitoes and flies, which makes them more helpful to the gardener than to plants. However, any insect that disposes of mosquitoes is more than welcome in my garden.
Hoverflies (syrphid flies, or flower flies) – look like small yellow jacket wasps and sometimes like small bees. Unlike the wasps, they do not harm humans. The larvae are voracious eaters of aphids, termites and ants while the adult feeds mainly on flower nectar and helps with pollination.
Green Lacewings (Aphid lions) – Green lacewing larvae feed on aphids and the other insects that the above group enjoys. They also eat nymphs and moth eggs, all of which makes them very helpful to the gardener.
Assassin Bugs, Pirate Bugs and Damsel Bugs – This group of bugs preys on aphids, spider mites, leafhoppers, thrips, a range of caterpillars and even one another if there is a food shortage. Pirate Bugs feed by pumping saliva into their prey and then drink the contents.
Tachinid Flies – Tachinid flies are parasites. They lay their eggs near a host, such as a caterpillar, or on the leaf where the caterpillar feeds and when the larvae hatch they burrow into the caterpillar to feed, killing it from within.
Braconid and Ichneumonid Wasps – These wasps are from a large and varied group. They are both parasitic. Depending on their size they attack aphids, grubs or caterpillars. Females inject eggs into host insects. The larvae hatch and grow inside the host. You can sometimes see evidence of their presence in a garden: some leave behind “aphid mummies” which are small and discoloured. Other braconids spin conspicuous pupal cocoons once they have emerged from a host. [Photo: Braconid Wasp cocoons on a tomato hornworm.]
Attracting Beneficial Bugs to Your Garden for Natural Pest Control
A major way of attaining a balanced ecosystem is to use natural pest control, which includes attracting beneficial insects to the garden. This won’t happen if you use commercial pesticides, which wipe out beneficial bugs along with the pests. It is best to save even homemade or purchased organic pest deterrents for extreme need.
Here are a few ideas that might help you reach this goal:
- Build bee and insect houses. These can be elaborate or as simple as having garden ornaments, pots or a log with holes drilled in it. This Insect House was found on Pinterest. Click here to see more about it.
- Keep aside a small part of the garden as a rough area with grasses and wildflowers to attract insects. Grow them in containers if you prefer.
- Plant only healthy plants. Weak plants attract insect pests. For example, if a plant has an infestation of aphids or whitefly it is probably too weak and stressed so you should remove it. Try blasting the plant with hose spray, or spray it with a soapy water spray – choose the method to suit the plant. Either way, you will get rid of most of the pests temporarily and leave no toxic residue. However, if the bug infestation is severe you could spray with Neem, but avoid using it when bees and other beneficial insects are on the plants.
- Make sure that your plants stay healthy. To do this you need to feed the soil with nutrients such as compost, rotted animal manure, or commercially produced organic fertilizers. See that the garden is well watered and then mulch it.
- Intersperse your crops with small clumps of plants that attract bees and other insects – nasturtiums, basil, and lavender are good. Try to have something flowering at all times. If you grow successive crops of beans and/or peas and some cucurbits (squash, pumpkins, cucumbers, gourds etc) this may suffice.
- Plant marigolds. They take up very little space and they kill eelworms and nematodes in the soil and attract pollinators.
- Plant Phacelia tanacetifolia, which is excellent for attracting beneficial insects and as a bonus you can dig it in as green manure at the end of the season.
- You could let the occasional lettuce or other green vegetables bolt to seed. When this happens, the flowers encourage beneficial insects and you can then let the seeds ripen and use them next season instead of buying seed.
When bugs attack our plants we want to get rid of them… fast: it’s as though their presence is casting doubts on our expertise as gardeners. But reaching for that spray, powder or those pellets is at best a temporary success. If you take that route you have to follow it religiously or the bugs return in greater numbers. You will probably get good crops but you will also get the harmful spray residue that clings to them – you couldn’t pick a tomato off a plant and eat it, warm from the sun, then and there.
If you choose to use natural pest control you work with Nature and build healthy soil, teaming with life and rely on beneficial insects to get rid of the pests. Your healthy plants attract fewer pests and the natural environment attracts beneficial bugs to dispose of them. Furthermore, you can eat a tomato straight off the plant, with no need to worry about toxic residues.
[Tweet “Grow plants that encourage beneficial bugs and provide them with shelter, where they can over-winter”] Although this natural pest control might leave you with a few nibbled leaves or an isolated caterpillar that escaped the assassination squad, you will have healthier plants, thanks to the rich soil they grow in and an absence of toxic residue.
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Tachnid Fly larva on a gypsy moth: John H. Ghent, USDA Forest Service, Bugwood.org
Hoverfly: Phil Sloderbeck, Kansas State University, Bugwood.org
Braconid cocoons on tomato hornworm: Chazz Haselein, Alabama Co-operation, Extension System, Bugwood.org
Green Lacewing: Frank Peairs, Colorado State University, Bugwood.org
Ladybug: Charles J. Sharp, Wikimedia Commons
(1)”Biological Control and Natural Enemies of Invertebrates” University of California Agriculture and Natural Resources http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn74140.html
Beneficial garden Insects http://www.no-dig-vegetablegarden.com/beneficial-garden-insects.html
Natural Pest Control http://organicdailypost.com/natural-pest-control/?hvid=4O0NbH