Beneficial Insects
Insects: the word evokes several mental images. The flies and mosquitoes who annoy us on hikes in the woods, the beetles who eat our garden produce before it’s barely had a chance to develop, the bees that pollinate our flowers, and the butterflies that beautify our yards. The truth is that there are estimated to be between 6 and 10 million species of insects on the planet and while we know very little about a vast majority of them, we do know that they are vitally important creatures.
Naturalist E.O Wilson called them “the little things that run the world” and argued that without insects, food chains would collapse, flowering plants would cease to exist, and everything that depends on them, including human civilization would disappear. Insects are critically important to our ecosystems and we would do well to conserve them.
Personally, I find insects fascinating and believe they are creatures worth caring for in their own right, whether or not they benefit us. But many people need to be convinced of their helpfulness. And others are inspired by a reminder of how amazingly useful insects are to our lives.
So let’s take a look at some of the ‘ecosystem services’ that insects perform for us and then discuss some of the ways we can use our yards and properties to care for them.
Decomposers
Decomposers are those insects that feed on dead or dying plant or animal tissues or on the manure of other animals. Think of them as the recyclers. They take plant and animal waste and cycle the nutrients back into the soil where it can be used again. Decomposers are essential in creating the humus layer of soil which is further broken down by microorganisms which then release nutrients such as nitrogen and carbon to the living plants.
Examples of decomposers are dung beetles, ants, blow flies, and springtails.
Predators
Predators are those insects that actively hunt for their prey. Cultivating a high variety of predators ensures that pest populations are kept in check since each species uses a different strategy for hunting or hunts specific prey.
While I know I said that all insects are essential to the ecosystem, some do tend to cause problems for us humans in the short term and are typically seen as pests by the average person. I admit that when I’m trying to grow cucumbers and masses of striped cucumber beetles start stripping my plants of their leaves, I think of them as a pest, too. However, instead of breaking out the pesticides which kill indiscriminately, I look for ways to attract the soldier beetles and braconid wasps to control the population. Attracting these predators keeps the pest population in balance over the long term, leading to greater biodiversity, less stress for me, and food for all.
Other examples of predatory insects include ladybugs, hoverflies, lacewings, and praying mantises.
Pollinators
These insects feed on nectar or pollen from our flowering plants and along the way they happen to transfer pollen between flowers which is essential for these plants’ reproduction. If you have fruit trees or a vegetable garden you will know how essential these insects are for ensuring you have a crop at harvest time. But pollinators are not only essential for our edible plants, but also for many of our flowering trees, shrubs, and other ornamentals.
We tend to think of bees when we think of pollinators, and certainly bees are effective pollinators. However, butterflies, wasps and even flies are also useful pollinators to attract to the garden.
How to Help Beneficial Insects in Your Own Yard
So, how do we help these beneficial insects? Whether you have a balcony, a backyard, or a community park that you care for, you have a role to play!
1. Don’t use pesticides!
This really goes without saying, but sometimes we need to state the obvious. Pesticides kill indiscriminately and damage the ecosystem for many of the insects we want. Besides, who’s to say that some of those insects that we think of as pests, might actually be beneficial to us in the long run.
2. Provide food for a long season
Think intentionally about the plants you put in your landscape. For nectar- and pollen-dependant insects, you want to provide flowering plants that extend the food sources through as much of the season as possible. In our area that means especially focusing on early spring and fall flowering plants as food sources are more scarce at those times of year. Don’t forget that flowering plants include trees, shrubs, and perennial flowers, even those we sometimes think of as weeds.
Speaking of weeds, we can also rethink our lawns as habitat and leave some of those plants that we normally consider weeds alone. “No-mow May” is a movement encouraging lawn-owners to leave the dandelions and other flowering plants in their yards for the early spring specifically to help the local bee populations for whom they are a significant food source. Similarly, several seed companies are now selling alternative lawn blends that provide food and habitat for native insects, beauty for the human occupants, and retain that soft lawn-like feel for recreational purposes. Bonus, many of these alternative blends are low-maintenance!
Finally, don’t forget about the insects that don’t feed on flowers! Leave that leaf litter in your garden or some downed wood in a back corner of the yard. Add compost to your flower beds. These are essential food sources for our decomposer friends in addition to habitat and nesting sites for particular insects.
3. Plant primarily native plants
“Ninety percent of the insects that eat plants can develop and reproduce only on the plants with which they share an evolutionary history”
In other words, ninety percent of insects are dependent on native plants for their survival. Studies have shown that “ecosystems dominated by nonnative plants are characterized by reduced insect diversity, abundance, and biomass” (source). Native plants are the best choice for supporting local insect biodiversity, which in turn supports biodiversity of other animals in the food web. If we want to promote biodiversity at all levels and mitigate species extinction, we need to prioritize native plants in our landscapes.
Now, some nonnatives in your garden are not going to destroy the ecosystem (unless they become invasive). I have some nonnatives in my garden because they serve another particular purpose or because I like the look of them. However, most of the plants in my garden are native perennials. They look beautiful, grow with minimal effort because they are adapted to the area, and support the native insect and wildlife populations.
For sources of native plants, I highly recommend Ontario Native Plants if you are in Ontario or Origin Native Plants if you are local to us in Guelph. If you are elsewhere, search specifically for a local plant nursery that specializes in natives as they will be able to help you know which ones are best suited for your environment.
4. Providing habitat for all stages of the lifecycle
When thinking about supporting insect populations, we need to think about support for them at all stages of their life cycle. Take moths for instance: many species live as caterpillars on the leaves of shrubs or trees but do not complete their life cycle in that same location. Instead, they drop to the ground where they pupate in the soil or in the leaf litter below. If the soil is compacted by regular lawn mowing and lack of nutrients or if there is no leaf litter present, these moths cannot complete their life cycle. If we would go to the effort of ensuring a local food supply for one stage of the insect’s life cycle, we must continue that care to the rest of their development.
One simple way to do that is to leave leaf litter on the ground. Leaf litter is a very important habitat for many types of insects. In addition, as I’ve already mentioned, it provides food for decomposers, who happen to loosen the soil in their decomposition process which in turn provides more habitat for those pupating moths and others.
Other insects need sticks or loosely piled rocks for habitat. These can be left lying naturally in back corners of the yard or they can be incorporated into the aesthetics of the garden (think wood or rock pile decorations or bug hotels).
My favourite strategy for providing habitat for the insects as well as other benefits to the general ecosystem of the landscape is to underplant trees with native plant gardens. This uses space efficiently, adds beauty by incorporating a variety of textures and colours at varying heights, and builds soil nutrition which benefits the trees as well as the flowers. As far as the insects are concerned they have soft soil, hiding places, and plenty of food and habitat for each stage of their life cycle.
When all is said and done I’m going to enjoy some rest in the garden observing the insects, celebrating life, and marvelling at the web that interconnects us.
