Calling a truce: making peace with ants in my garden

I’ve been gardening for almost 25 years here in Ottawa. Early on, as a beginner, I was a loyal listener of CBC Radio’s Gardening Phone-in show on Ontario Today. On Mondays at noon Ed Lawrence, then head gardener at the Governor-General’s residence, answered questions and offered gardening advice. It seemed that every week someone called in asking how to get rid of ants, and Ed recited his boric acid recipe for killing them. Apparently, ants were a formidable enemy in the garden.

Armed with Ed’s weapon, I waged war on ants for several years. They just kept coming back. Being on the lazy side, I readily admitted defeat and just put up with them. In fact, I stopped battling insects all-together and put down the pesticides, boric acid, soapy and boiling water, vinegar, et cetera. I called a truce. At the time, I didn’t realize how important this decision would be for the future of my garden and its wildlife visitors.

Once I began converting our yard to pollinator and bird habitat, I learned that ants are actually my allies in the garden.

Ants aren’t very good pollinators, but they inadvertently do some pollination while visiting flowers to drink nectar. Ants on Oval-leaved Milkweed (1st photo), and on a Pussy Willow catkin (2nd photo).

Ants plant seeds

In my garden, one of ants’ most valuable roles is as seed dispersers.

I want to include more spring-blooming, native woodland plants — like Dutchman’s Breeches, Bloodroot, Hepatica, Trillium, Trout Lily, Wild Ginger, and Large-flowered Bellwort — in my garden to provide food for early pollinators. Unfortunately, they’re tricky to grow from seed because the seeds are double-dormant, meaning that they require two cycles of warm, then cold weather before they’ll germinate. The seeds are also hydrophilic — if they dry out, they won’t germinate. For these reasons, I’ve never tried to grow native spring-blooming woodland plants from seed. Instead, each year I buy a few from local native plant nurseries.

Lucky for me though, now that I have a some mature plants, ants are spreading their seeds for me and creating more free plants. Ant seed dispersal is called myrmecochory. The seeds of spring-blooming woodland plants each have a fleshy, nutritious structure attached to them, called an elaiosome. Ants collect the seeds, drag them to their nests, eat the elaiosomes, and then dump the seeds into their underground trash area or outside of the nest. The end result is that ants have planted the seeds; seeds are planted before they dry out, where they won’t dry out, and they can wait out the changing seasons until it’s time to germinate.

To see amazing close-up photos of ants collecting Trillium seeds, visit Feeling Antsy, a blog post by the Roads End Naturalist.

Now that my parent plants are a few years old, I’ve begun to see little seedlings dotted nearby. I hope the ants will eventually create generous patches of flowers to provide lots of nectar and pollen for queen bumblebees and early solitary bees.

A mature Bloodroot plant (1st photo), and a cluster of seedlings (2nd photo). (May 1, 2022)

Hepatica (1st photo) and a little seedling (2nd photo. (April 25, 2022)

A bumblebee queen visiting Large-flowered Bellwort (1st photo), 2 mining bees at the flowers (2nd photo), and a Bellwort seedling (3rd photo). (May 10, 2022)

A bumblebee queen visiting Dutchman’s Breeches (1st photo), and an increasing patch of the plant (2nd photo). (May 4, 2022)

Ant seed dispersal was obvious to me near a patch of Wild Ginger that I planted beneath an old Japanese Maple. Ants had unfortunately been nesting in the back of our house. A new patch of Wild Ginger seedlings then sprung up between the mature Wild Ginger and the area of the house where they’d been nesting. Ants planted dozens of new Wild Ginger plants.

Ants gathered seeds from Wild Ginger (right), and spread the seeds in a trail toward their nest to the left, creating many new Wild Ginger seedlings. (May 2, 2021)

Ants improve soil

Ants also help me in the garden by improving the soil. According to Fine Gardening magazine, ants are like tiny rototillers:

“Tunneling ants turn over as much soil as earthworms do, aerating the soil and redistributing nutrients. Ants are also part of the world recycling crew: acting as scavengers, collecting dead insects and turning them into fertilizer for your soil.”.

Fine Gardening, Ants Aren’t Your Enemy, by Steven N. Handel and Christina M. K. Kauzinger

Before earthworms were introduced into Canada, insects like ground beetles and ants did the work of turning soil. I assume that native ground-nesting bee tunnels also turn soil in my garden.

Ants are bird food

By accident, I discovered that ants are also bird food. Ants had mad a nest near our backyard stream water feature. While examining photos of a Red-eyed Vireo that visited the stream, I discovered that it had an ant in its beak. The bird wasn’t just visiting the stream for a drink and a dip, it was also having a snack.

A Red-eyed Vireo, in lilacs beside the stream, with an ant in its beak (1st photo). Perhaps it was feeding ants to its fledgeling, the fluffy bird on the right (2nd photo). In the third photo, you can see a Bloodroot seedling growing next to the stream’s waterfall reservoir, planted by ants nesting near the stream. (August 29, 2020)

Later that summer, I watched a Blue Jay eating flying ants as they left the ant hill near the stream.

I’ve also seen a Northern Flicker foraging for insects in the vicinity of another ant hill in our back lawn.

I assume this Northern Flicker was eating ants because it foraged for some time near an ant hill in our lawn. (August 3, 2021)

Ants also have a close relationship to another so-called garden pest — aphids. Ants eat sweet aphid excrement, called honeydew. So, ants will ‘farm’ aphids, carrying them to different plants where the aphids can suck liquid from leaves and stems, and then pass honeydew for the ants to eat.

Early one spring, I watched a Ruby-crowned Kinglet foraging for insects in a Chokecherry tree. On closer inspection of the photos, I realized that the Kinglet was eating ants and aphids from the leaves.

This Ruby-crowned Kinglet was foraging for insects in a Chokecherry tree. In these photos, you can see both ants and tiny black aphids on the leaves (last photo). (May 10, 2021)

Chokecherries seem to be a favourite food of aphids. Our trees continued to attract ants and their aphid buddies throughout the summer. In June, I watched Chickadee parents collecting aphids from Chokecherry leaves and then feeding the aphids to their young.

Chickadee parents collecting aphids from Chokecherry leaves to feed to their fledgelings: fledgeling Chickadee (1st photo), parent collecting aphids (2nd and 3rd photo), and feeding junior (4th photo), (June 4, 2021)

More Good than Bad

After some Googling, I learned that ants are beneficial in other ways. They also help control garden pests (Got Ants in Your Plants? Here’s What You Need to Know), and even help regenerate forests (Flower Power: research highlights the role of ants in forest regeneration).

I admit that there are certainly times when ants are troublesome. Over the years, a few of my plants suffered or died when ants made nests right under them. This is a rare occurrence though. Ants like to nest in dry places. I found that piling leaves or mulch around an affected plant holds moisture in the soil, making it less hospitable and discouraging the ants from nesting in that particular spot.

Aphids, spread around plants by ants, can cause leaves to become shriveled or yellowed. This is a temporary affliction and the plants eventually recover. If there are enough aphids to cause widespread damage, ladybugs and other predatory insects move in to control them.

All in all, ants do more good than bad. I’m willing to put up with them for free plants, improved soil, and to feed baby birds.