Beyond the Monarch: Discover Other Fascinating Travelers in Your Garden!

Ah, May… FINALLY! The month when everything comes alive in Canadian gardens. The birds return with a fanfare, the buds burst open… and of course, monarch butterflies monopolize social media with their great migration!

But they’re not the only snowbirds in the insect world!

Right now, as gardens are coming to life, a symphony of fascinating movements is taking place beneath our feet and above our heads. Migration isn’t just about crossing a continent from north to south; it’s any organized movement that allows a species to adapt to changing conditions.

Before I had my precious air conditioner, I often “migrated” to the basement for a week or two to escape the heat waves. Yes, that fits the definition of migration!

Ready for a journey of discovery into the world of insects in the garden? Fasten your seatbelts, we’re taking off… and we’re going to go deep! (Actually, we’re going to go in all directions!)

Frequent Flyers

Of course, we cannot ignore the migration of the monarch butterfly, this star of the insect world, which has long captured our attention with its 4,000-kilometer journey. It is a remarkable and rather curious feat: the individuals that make the journey from north to south do so all at once, but those returning from south to north follow one another in several generations.

The Monarch Butterfly

The butterfly born in the south travels a few hundred kilometers, stops, and has babies. These will travel a few hundred kilometers, stop, and in turn produce a new generation. And so on, until they reach our flower beds.

But this iconic butterfly isn’t the only one to undertake great journeys. In fact, I have to admit that its reputation as a great traveler overshadows the migration feats of other insects. (Don’t get me wrong, I love monarchs, but I’m just taking the spotlight off them for a moment!)

The Painted Lady Butterfly

Did you know that the painted lady butterfly (Vanessa cardui) makes almost the same migration as the monarch butterfly? It travels thousands of kilometers from the southern United States and Mexico to Canada every spring. These colorful butterflies cannot survive our harsh winters, and like monarchs, they take turns over several generations to complete their return journey.

It is probably less well known because it is the most common butterfly in the world, unlike the monarch, which is an endangered species. Found in northern Europe, the painted lady migrates 6,000 kilometers to sub-Saharan Africa in winter, crossing the Mediterranean and even the Alps!

The Pieridae

Staying in Europe, pierid butterflies—the white or yellow butterflies with a little black that we often see in our gardens—also migrate. Tagging studies have shown that individuals travel up to 500 km.

Curiously, although the same families of butterflies exist in North America, their migrations are much less pronounced. They travel only a few dozen or hundred kilometers at most. Some experts speculate that the greater availability of food on our continent could explain this difference—why migrate when the buffet is open all summer long? Hibernating in the ground as nymphs becomes a more rewarding strategy.

As someone who is rather laidback, I have to say that I agree with our American pierids. Between sleeping for a few months and traveling 500 km, it’s an easy choice, isn’t it?

Oh, and it’s not just butterflies that migrate such long distances! Do you know what the most terrifying flying insect is (in my humble opinion, anyway!)? It’s an insect that can reach speeds of 70 km/h, has 360° vision, and whose larvae can sometimes eat small fish! Have you guessed?

The Dragonfly

The dragonfly! A fascinating predatory insect in its own right, but what if I told you that it also travels 3,500 km to the south? That’s the case for the June Anax, which has three generations per year: one goes south, one returns north, and one takes it easy during the summer. No relay race here.

Have you ever wondered how insects know where to go? Because honestly, when I see a cloud of bugs “captured” by streetlights, I wonder! I did some research and… if I explain in detail how it works, you won’t like me!

So I’ll just simplify by saying that the sun (the length of the day and its position in the sky), the Earth’s magnetic field (yes, just like a compass!), visual and olfactory landmarks (oh, look, a pretty mountain!), air currents (some insects fly at altitudes of up to 2,000 meters!), and genetic programming are all different indicators that guide insects along the right path.

In short, they don’t rely on highway signs!

Vertical Migrations in the Soil

Pollinators and predators are all well and good, but as gardeners, we mustn’t neglect decomposers. So let’s get back down to earth. While some insects fly through the sky, others embark on an equally important journey, but this one is vertical. The underground migration of insects is a little-known phenomenon that nevertheless has a direct impact on the health of our soil and gardens.

Let’s start with our silent allies, earthworms (technically, earthworms aren’t insects, I know, but it’s impossible to talk about garden soil without mentioning them!). Even though I’ve already told you that they’re an invasive species that’s harmful to our ecosystems, there’s no denying that they do a great job in the garden. But Canada being what it is, what do these little intruder workers do when the ground freezes solid? Let’s face it: their soft, slimy bodies don’t seem like they’re the most resistant to the cold.

The Earthworm

As winter approaches, earthworms begin their descent into the depths, digging tunnels all the way to Mexico as they move from lawn to lawn!

Gotcha! But no, it’s not heading south! In fact, it goes underground to a depth of around 30 centimeters—but sometimes up to a meter below the surface—where the temperature remains stable at around 4 to 8°C (39 to 46?). It’s hard to believe that you can warm up underground: after all, the basement is always the coldest place in the house! But this is also true in summer, precisely because of the stable temperature underground. Whether it’s freezinf or there’s a heatwave, the temperature deep underground varies very little.

In worms, this vertical migration is accompanied by impressive physical adaptations: their metabolism slows down considerably and, in some species, large amounts of sugar are stored in their bodies to protect their cells. (I know that nitpickers will say that this is hibernation, not migration, but hey! Why couldn’t it be both!?)

Sugar?

This sugar doesn’t give you love handles, by the way! We’re not talking about a bear storing fat. Rather, it prevents their bodies from freezing. If you put oil, water, and alcohol in the freezer, you’ll see that they don’t all freeze at the same rate. The alcohol may even remain liquid if you’ve used spirits. This is because different liquids freeze at different temperatures. Dissolved sugar, much like alcohol, lowers the critical temperature in the worm’s body.

In spring, guided by rising temperatures and humidity, the worm gradually moves back up, creating a network of tunnels that aerates your soil as effectively as a mechanical aerator.

Other Insects That Migrate Downward

But worms are far from the only creatures that “migrate downward” to protect themselves from winter. When you turn over your soil in the spring, you are sure to encounter a wide variety of insect larvae. I should mention rose chafer beetles and cockchafers, two large, plump white worms, and crane fly larvae, which often live in grain fields and lawns. Other deep-dwelling travelers include centipedes and millipedes, which are not insects but are very common in gardens!

Although they only descend a few inches into the ground, they also contribute to a harmonious awakening in spring. They aerate, decompose, and hunt in secret as soon as the soil warms up a little, making your May gardening much easier.

Seasonal Movements

While continental migrations are impressive in their scale and underground migrations are mysterious, local seasonal movements are just as noteworthy. Throughout the seasons, insects must move to find food and mates. It’s one thing to follow an internal magnetic compass or gravity, but tracking the blooming of flowers and pheromones is an equally impressive skill.

The Example of Wild Bees

Take wild bees, for example, many of which are solitary species. In spring, they emerge from their wintering sites—often hollow stems or tunnels in the ground—and begin a journey based on the sequential flowering of plants. For example, forest flowers may bloom more quickly on the south side of forests.

Microclimates created by human structures or the landscaping preferences of neighbors also create variations in food availability. Insects sometimes have to move to a new neighborhood to find a food source once the snowdrops have wilted!

The Giant Green Water Beetle

Aquatic beetles offer another fascinating example of springtime movements. During winter, several species such as the giant green water beetle (Dytiscus marginicollis) hibernate in the mud at the bottom of ponds. In spring, once the ice has melted, they rise to the surface and begin to become active.

As the sun becomes more and more present, their spring pond sometimes shrinks. In some cases, it even dries up! The diving beetles fly away (yes, they are aquatic beetles that can fly!) to more permanent habitats. You know, the little creature that was splashing around in that muddy hole in your lawn and then disappeared? Well, that might have been one of them!

Climate Change and Disruptions to Migration Cycles

There’s no getting around it: your grandmother is right when she says that “things weren’t the same before.” Insect migration relies on many environmental signals, and these are constantly changing, which creates some timing issues!

It has been shown that butterflies are returning from their migrations 2 to 10 days earlier than they did ten years ago. However, the signals that herald spring for butterflies are not always the same as those for their favorite plants.

So the butterfly arrives, ready to reproduce, but its host plant has not yet developed the tender young leaves where it can lay its eggs. What to do? Lay eggs elsewhere and hope that the caterpillars will find this new plant to their liking? It’s like organizing a date where one of the partners arrives two weeks before the other.

Even creatures living deep underground emerge a few days earlier. Several insects that complete their metamorphosis in spring also emerge earlier than they did twenty years ago. In the absence of late spring frosts, this may seem advantageous for small butterflies and other delicate insects, but this early emergence also exposes them to risk from late frosts.

Observe and Encourage These Migrations in the Garden

After this journey through the unexpected migrations that animate our gardens, one question remains: how can we, as gardeners, encourage these movements that are essential to the balance of our ecosystems?

The first step is simply to observe. Nature usually does very well on its own, and observing it helps us understand it better.

Here are a few tips: don’t play in the soil when it’s cold, as this is good practice for taking care of the little underground world; diversify your spring landscaping; and use good mulch to keep your soil warmer and allow decomposers to extend their working season.

Tell me, on this first day of May, which insects have already visited you? Have you seen your first butterfly? Your first little green bee? Make me believe it’s summer!