Hariette Henry – Halton Master Garden
Creating an ecologically balanced home garden, teeming with life and variety, where no pesticides or herbicides organic or otherwise are needed, is achievable if you take a time to do it.
Insects are part of the ecosystem of a garden and often they go about their business with little notice from gardeners. It might be surprising to learn that some 80% of the world’s animals are insects. There are between two and twenty million insect species on the planet and only one million have at this point been named.
What is also surprising is that only one percent of the insects in our gardens are actually harmful. The other 99% of insects are either benign or beneficial.
What is also surprising is that only one percent of the insects in our gardens are actually harmful. These are the creatures who consume our plants, introduce disease, bite our flesh, feed on our pets and generally cause economic, aesthetic and/or medical damage.
The other 99% of insects are either benign or beneficial. They are beneficial because many of them are pollinators. That is to say, that they consume pollen and nectar, converting these plant-sourced carbohydrates into energy for movement as well as using them to increase their fertility.
They are predators “entomophageous” – meaning they are insects who eat other insects. All these tiny predators are a vital part of our gardens. Their intent is not so much to help you control pests but rather to survive and reproduce. The result is obviously a clear win-win for both insects and gardeners.
This system is “tritrophic” – meaning it involves three layers of consumption. The plant which is at the bottom of the food chain, the herbivore or prey who feeds on the plant and finally the predator or meat-eater whose role is to consume the herbivore.
This system is “tritrophic” – meaning it involves three layers of consumption. The plant which is at the bottom of the food chain, the herbivore or prey who feeds on the plant and finally the predator or meat-eater whose role is to consume the herbivore. These predators have varying consumption methods, they can be true predators, parasites or parasitoids (parasitoids often raise their young within a host, eventually killing it.)
In order for this predator/prey cycle to function effectively, gardeners need to take themselves out of the way and let nature take its course. This can be quite difficult to do especially when a prized plant is involved. However the likelihood of an infestation of aphids on your milkweed killing the plant is actually quite low. The plant may not look good for a period of time but it’s chances of survival are excellent.
So what is the secret to creating the right environment for beneficial insects?
First and foremost, is to maintain a pesticide free environment. A pesticide might eliminate most of a population of prey insects attacking your plants but a few will survive and be resistant to the chemical, they then pass that trait on to their offspring. Beneficial insects are very often more susceptible to pesticides as not only do they come in physical contact with the spray but they are also exposed through their consumption of the contaminated prey.
An eco-friendly garden is a stable garden and gardens become stable if they are diverse. Incorporate different species and sizes of trees, shrubs and perennials and annuals in order to meet the needs of a great variety of organisms
Select as much as possible, native species. Our native plants have evolved along with the beneficial insects over millennia and so they are best adapted to serve as food, shelter and breeding grounds for indigenous fauna. To achieve a maximum of biodiversity, it’s recommended that you reproduce the plant strata present in the natural environment. Introducing shrubs and herbaceous plants under or around trees is a good way to reproduce the vertical stratification of forests.
Another important consideration is to make sure you have plants that will flower continually so that pollinators, and even birds and small mammals can feed from springtime through to autumn. It is also important to group flowers of the same species together in small beds, (consider 4’ x 4’) rather than scattering them here and there around the garden. Keeping plants together makes things easier for beneficial insects, who’ll find the pollen and nectar they feed on more readily. And kept together this way, plants will make a better visual impact. Pollinator activity can also be encouraged by placing nectar-producing plants in a sunny spot protected from the wind.
It is not necessary or even desirable to do a major housecleaning of flowerbeds in the fall since dried stems and dead leaves provide winter shelter for a number of organisms beneficial for the garden.
Installing accessible sources of water in the garden throughout the summer months creates a welcoming habitat for insects and other animals. A low saucer filled with pebbles in various parts of the garden ensures that beneficial insects will not drown.
The following are a few of the beneficial insects you might like to attract to your garden;
TRUE BUGS; Assassin bugs, Big-eyed bugs, Damsel bugs, Minute pirate bugs and certain predatory Stink Bugs:
- These bugs consume aphids, asparagus beetle, caterpillars, Colorado potato beetle eggs and larvae, four-lined plant bugs, sawfly larvae, spider mites, whiteflies, and many other insects and eggs.
- Some true bugs are plant feeders but many are predacious at both the nymph and adult stages
- Plants that will attract them: Caraway (Carum carvi), Cosmos ‘White Sensation’ (Cosmos bipinnatus), Fennel (Foeniculum vulgare), Alfafa (Medicago sativa), Spearmint (Mentha spicata), Peter Pan Goldenrod (Solidago virgaurea), Marigold ‘Lemon Gem’ (Tagetes tenuifolia).
PREDATORY BEETLES; Fireflies, Ground beetles, Ladybugs, Lady beetles, Ladybirds, Rove beetles, Soldier beetles, Leatherwings and Tiger beetles:
- Some of the pests predatory beetle larvae eat are grasshopper eggs, caterpillars, aphids and mealybugs. The adults consume nectar with many species also consuming other insects.
- Plants that attract Lacybugs are: Fern-leaf Yarrow (Achillea filipendulina), Common Yarrow (Achillea millefolium), Carpet Bugleweed (Ajuga reptans), Basket of Gold (Alyssum saxatilis)
- Plants that attract Ladybug larvae are: Dill (Anethum graveolens), Golden Marguerite (Anthemis tinctoria), Butterfly Milkweed (Asclepias tuberosa) , Four-wing Saltbush (Atriplex canescens), Coriander (Coriandrum sativum), Queen Anne’s Lace (Daucus carota), CA Buckwheat (Eriogonum fasciculatum), Fennel ( Foeniculum vulgare) and many others.
LACEWINGS; Dustywings, Brown Lacewings, Green Lacewings:
- Lacewing larvae prey upon aphids, small caterpillars and caterpillar eggs, other larvae, mealybugs, whiteflies and more. Adults eat honeydew, nectar, and pollen and some eat other insects.
- Plants that attract Lacewings Caraway (Carum carvi), Cosmos ‘White Sensation’ (Cosmos bipinnatus,), Fennel (Foeniculum vulgare) and Dandelion (Taraxacum officinale).
TRUE FLIES; Tachinid Flies, Gnats, Mosquitos and their relatives:
- There are more than 1,300 North American species of parasitic flies. Most resemble houseflies but with short, bristly hairs on the abdomen. All develop as internal parasites of other insects, including many garden pests. Usually, the adult female attaches its egg to the host insect, which is then consumed by the larva, but there are several other patterns: eggs laid on host, eggs laid into host, eggs laid on foliage to be eaten by host, live larvae laid on or near host, and live larvae laid into host. Larvae feed internally on caterpillars,
beetles, bugs, earwigs and grasshoppers. Adults feed on nectar, pollen and honeydew.
- Plants that attract Tachinid Flies are: Golden Marguerite (Anthemis tinctoria), CA Buckwheat (Eriogonum fasciculatum) , Lemon Balm (Melissa officinalis), Pennyroyal (Mentha pulegium), Parsley (Petroselinum crispum), Phacelia (Phacelia tanacetifolia), , Tansy (Tanacetum vulgare), Crimson Thyme (Thymus serpyllum coccineus).
SPIDERS; Predatory mites, Spiders:
- All of the more than 3,000 North American species of spiders are predatory. Their diet depends on the species, but can include aphids, beetles, cutworms, fire ants, lacebugs, spider mites, squash bugs and tobacco budworms.
- Predatory mites, like the Amblyseius swirskii contained in the packet in the adjacent photo, can be introduced into greenhouses and
gardens to help keep pest numbers in check.
- Spiders and predatory mites thrive in a richly diverse environment. Use many different structures within the landscape.
If the prospect of gardening for beneficial insects seems a bit daunting don’t be discouraged. The best approach is to take your time. Make changes slowly! Set a goal of adding only as many of the recommended species as you can manage, in the right quantities to start with. Before you know it you will have a garden teeming with life.
Further Reading;
Hoffman Fred, Permaculture News, Permaculture Research Institute, https://www.permaculturenews.org/2014/10/04/plants-attract-beneficial-insects/
Queirolo, Joe; Fine Gardening, Issue 26, https://www.finegardening.com/article/attracting-beneficial-insects
Walliser, J; GOOD BUG, BAD BUG, Who’s Who, What They Do and How To Manage Them Organically, St, Lynn’s Press, Second Edition 2011
Walliser, J; Attracting Beneficial Bugs to your Garden, A Natural Approach to Pest Control, Timber Press, 2014
Space for Life, Gardening for biodiversity, https://espacepourlavie.ca/en/gardening-biodiversity
Bylands Nursery, 8 Ways to Attract Beneficial Wildlife To Your Garden, http://www.bylands.com/blog-entry/8-ways-attract-beneficial-wildlife-your-garden
Mother Earth News, Organic Pest Control: the Best Plants to Attract Beneficial Insects and Bees,
Mother Earth News, Enlist Beneficial Insects for Natural Pest Control, https://www.motherearthnews.com/organic-gardening/natural-pest-control-beneficial-insects-zm0z12amzhir
Halton Region Master Gardeners 