A Garden to Welcome Beneficial Insects

Spring excites us as we plan our gardens. Important to consider as part of a plan is how to attract beneficial insects. These tiny garden allies —pollinators, predators, and decomposers — help maintain a balanced environment. The importance of pollinators is well-documented. After reading Jessica Walliser’s Attracting Beneficial Bugs to Your Garden (2nd Edition, 2022), it became clear to me that other insects visiting the garden also play crucial roles.

Pollinators such as bees, butterflies, moths and flies are essential for the reproduction of many plants. They transfer pollen from one flower to another, facilitating the production of fruits, vegetables, and seeds.

Predatory insects, including ladybugs, beetles, lacewings, true bugs, damselflies, dragon flies, praying mantids, tachinid and syrphid flies and parasitic wasps, help control the harmful pest populations. They prey on aphids, caterpillars, and other destructive insects that can wreak havoc on garden plants. By keeping pest numbers in check, these predators help maintain a balance, promoting a healthier garden environment.

Insects like beetles and certain types of flies play a vital role by breaking down organic matter. These decomposing insects help recycle nutrients back into the soil, enhancing its fertility and structure. This natural process supports plant growth and contributes to the overall health of the garden ecosystem.

With these benefits in mind, the next step is figuring out how to create an “insectary garden”, one with a welcoming ecosystem for these insects. Creating a garden that attracts and supports beneficial insects involves thoughtful planning and plant selection. Let us look at the steps you can take to build a welcoming garden.

The first step is to ensure you grow a range of plants that bloom from spring to fall, to provide a steady supply of nectar and pollen. Include various flower shapes, heights, and colours to accommodate different insects’ mouthparts. Look first to native plants which are adapted to our growing conditions and have an important relationship with native bees and other beneficial insects. Non-native annuals are also an important food source, but it is advisable to avoid newer hybrids with many petals, which can restrict access to nectar and pollen. Sunflowers, another annual, are beneficial for insects, but avoid pollenless varieties grown primarily for the floral industry. I have both annual and perennial herbs in my garden and always leave some to flower for the visiting insects.

The plants in my garden that attract beneficial insects are numerous and include coreopsis, cilantro, cosmos, sunflowers, shasta daisy, lovage, sweet alyssum, oregano, coneflower, rudbeckia, goldenrod, asters, monarda, feverfew, verbena, golden Alexanders, milkweed, zinnias, lavender, and cardinal flower. I also grow sweet cicely (Myrrhis odorata), an early flowering culinary herb that allows me to reduce sugar in recipes and is highly attractive to beneficial insects such as bees, tachinid flies, and syrphid flies.

The spring flowers from serviceberry (Amelanchier spp.) and the autumn flowers from seven-son tree (Heptacodium miconioides) illustrate that tree and shrub flowers are also important for both nutrition and habitat. Native flowering shrubs such as flowering raspberry, nannyberry, and gray dogwood are recent additions to my garden.

The practice of companion planting involves strategically placing plants that benefit each other. For example, annuals like marigolds and alyssum with their scent can deter pests from tomatoes and attract hoverflies and predatory wasps.

Having a diversity of plants in your garden can make it more difficult for pests to find their desired host plant.

I marvel at the ability and strength of a bumblebee pushing itself into a flower to access food sources. However, parasitic wasps and hoverflies lacking that heft appreciate the open, umbel flowers of dill, lovage and fennel. Consider leaving the flowers of bolting vegetables such as lettuce for them to enjoy. Embrace a bit of messiness!

The second step for attracting beneficial insects is to provide habitat with shelter and breeding sites as well as safe watering spots such as a shallow dish with stones as a landing area. A sun-baked spot between a garden path and a garden bed provides open soil for soil dwelling insects such as native bees.

Beetles benefit from mulched or stone areas. You may consider adding a beetle bump, a mounded island planted with bunch grasses and flowers for beetles to shelter during the day. It can be an aesthetically pleasing habitat in your garden.

Change your clean-up activities in the fall by leaving the leaves for overwintering insects and providing soft landings for moths and butterflies falling from trees who will overwinter in the leaf litter in different life stages. Also let stalks and stems stand for nesting sites. Delay garden cleanup in the spring until beneficial insects have emerged. If trimming in spring, cut stems to 30 cm and leave them or bundle them together and move to a sheltered spot for insects to emerge.

We can learn from farmers and commercial vegetable growers who plant an insectary border around their crops to attract beneficial insects and control plant pests. We can do the same in our gardens by having plants known to attract beneficial insects planted throughout our flower and vegetable beds. Not all beneficial insects are strong flyers or venture far from where they are born, so if they do not find what they need they might not survive in your garden. Even the strong fliers who cover long distances will not stop at your garden if they do not find available prey such as aphids for their young to survive.

It is recommended that chemical pesticides be avoided because they will harm beneficial insects along with the pests they target. Stay away from use of insecticides, even those labelled organic, as they also will harm beneficial insects. Encouraging a balanced ecosystem will naturally keep pest populations under control.

Inviting beneficial insects into your garden boosts plant health and productivity. Embrace the natural balance and let nature’s industrious workers thrive. Often, the best practice is to stay out of nature’s way. You need some bad bugs to attract good ones, so aim for balance. Identify the insects in your garden. Most are beneficial – only 1% are pests. Learn more from resources like Wild Pollinator Partners and Fletcher Wildlife Garden. Enjoy watching how your garden supports these vital creatures, described by E.O. Wilson as “The little things that run the world.” 