One of the most powerful tools of the organic gardener is a healthy garden ecosystem, full of predator insects to help with the fight against garden pests. Let the insects do the work of keeping the pests to a manageable level, so that you may enjoy the show that nature provides.
Avoiding pesticides may be the first step in making sure the population of predator bugs is high in your garden but there is much more you can do to attract and keep these visitors there. Understanding the life cycle and feeding habits of the insects you hope to attract can go a long way in setting up the ideal environment to encourage them to visit and stay. Surprisingly, planting flowers and keeping pest insects around will be the most effective way to attract the top predator insects.
Praying Mantis – Top of the Insect Food Chain
Praying mantises are vicious hunters, eating anything they can catch, including some small animals. This sometimes means that insects that you want in your garden may fall prey, such as butterflies or even other smaller praying mantises, but the good that is done much outweighs this fallback. (1)
As soon as praying mantises are born, they are ready to start eating other insects. They are born as miniature versions of the adults, with the same feeding habits, but of course they feed on smaller prey. They are territorial and tend to stay where they were born given that they have enough food available. This means that, depending on the size of your garden, you may only have room for one or two of these predators. Good news is that they will probably stick around all season and breed in your yard. (2)
Praying mantises can be attracted to the garden by having many plants that can provide shelter for them. Roses, raspberries, shrubs, and tall grasses are all good choices. If you find a praying mantis outside your garden, catch it and bring it to your garden. If it likes the environment, it will probably stay. You can also look for praying mantis egg cases and bring them into your yard or even purchase an egg case, which are available on Amazon among other sources. (3)
Source: huge mantis eat two bees at one time, by mituro36
Braconid Wasp – The Tomato Worm’s Worst Nightmare
Braconid wasps are a family of small parasitic wasps. The method of attack and target of attack depends on the specific species, but one particular wasp that is especially beneficial for the gardener is the cotesia congregatus. These small wasp lay their eggs inside the tomato worm. When the larvae are ready to pupate they chew through their host forming small white oval cocoons all over their backs.(4)
I remember the first time I saw a tomato worm on my tomato plant covered in these cocoons. I was repulsed and quickly threw the caterpillar out of the yard. I later realized the mistake I made, as I had gotten rid of the many wasps that I was hoping to attract to the garden. Had I kept the tomato worm in my garden, it would have provided the home needed for the many wasps on its back to emerge, and hopefully stick around.
The adult wasps feed on nectar from flowers, so you can encourage them to visit and stay in your garden by growing plants with small flowers such as dill, fennel and mint (5).
Source: Parasitoid wasp vs. bird cherry-oat aphid (1 of 2), by Pests and Natural Enemies
Lacewing – Watch out Aphids for These Small but Effective Predators
Lacewings are a family of flying insects that feed on small insects while they are in their larvae stage. Although the adults of some species feed on insects, most feed on nectar, pollen, and honeydew. The larvae eat a wide variety of insects such as mealy bugs, psyllids, thrips, mites, whiteflies, aphids, small caterpillars, leafhoppers, and insect eggs. (6)
There are commercial sources of lacewings, that can be released into the garden. This is especially useful for infestations, but natural attractions methods are also available. Providing lots of flowers for nectar and shelter is important to keep the adults happy. Having some pest insects such as aphids present is also important to keep the larvae fed. Spraying aphids with a mixture of sugar water, about 1 tablespoon of sugar per cup of water, can stimulate aphid honeydew. This will bring the aphid infestation to the attention of nearby lacewings. (7)
Source: Green lacewing larvae vs. bird cherry-oat aphid, by Pests and Natural Enemies
Hoverflies – An Amazing Pollinator and Predator
The hover fly is a small fly that is yellow and black, making it resemble a bee or wasp. This fly has the amazing flying ability to stop midair and fly backwards. Similar to the lacewing, the adults feed on nectar while the larvae feed on aphids and other soft-bodied insects. Because of this, the hoverfly is beneficial to the garden as both a pollinator and predator insect. (8)
Since the adults feed on nectar, the best way to attract them to the garden is by planting flowers. Fragrant herbs such as oregano, garlic chives, sweet alyssum, buckwheat, and bachelor buttons all work really well. (8)
Source: Hoverfly and Aphids, a fleeing aphid alerts another, by John Dunstan
Make your Garden a Healthy Ecosystem and it Will Work Like One
In the end, organic gardening is about trusting nature and accepting some flaws in your harvest in exchange for healthier produce and a sustainable environment. The ecosystem with all the insects, beneficial and pest, is part of the wonder that your garden provides. Appreciate the pest insects because without them you would have no predator insects. Then what would happen when the neighbour aphids got to your garden?
Sources for this article include:
(1) Animal Corner: Praying Mantis
(2) Beneficial in the Garden and Landscape: Praying Mantis
(3) Gardening Know How: Praying Mantis Information- How To Attract A Praying Mantis To The Garden, by Nikki Phipps
(4) Beneficials in the Garden and Landscape: Braconid Wasp on Hornworms
(5) Mother Earth News: Braconid Wasps: Good or Bad for the Garden?, by John Stuart
(6) University of California: Green lacewings
(7) Mother Earth News: About Lacewing Flies- How to Attract Lacewings to Your Garden, by Barbara Pleasant
(8) Gardening Know How: Hover Fly Information: Plants That Attract Hover Flies To The Garden, by Jackie Carroll