The
Monarchs are Coming! The Monarchs are Coming!
by
Monika Smith, Master Gardener
In
mid to late March, something extraordinary happens in Mexico. Monarch
butterflies (Danaus Plexippus) migrate north after sheltering in the
Oyamel fir tree forests (the eastern perimeter of the Mexican state of
Michoacán) to start their breeding season, an eight-month multi-generational
migration of four successive generations to the prairie provinces and Eastern
Canada then back. A typical monarch life span is 2 to 6 weeks, but the
final leg of migrating monarchs can live up to 9 months flying south.
The Western population, call B.C. home, and winter in California. Our
monarchs, the Eastern population flies to Central America, which can be
2500 to 3000 miles. Not all monarchs migrate! These beautiful, large
butterflies with orange, black and white colouration are distinct and have become
a flagship of conservation. By the way, a group of butterflies is officially
called a kaleidoscope. Groups of caterpillars are called an army.
There
are established sanctuaries, such as the UNESCO Monarch Butterfly Biosphere
Reserve near Mexico City providing the right temperature and humidity to
overwinter. Monarchs have lived in the southern prairie provinces for
millennia, but they are now an endangered species due to habitat loss
and modern agriculture. In 2025, iNaturalist recorded 1,500 observations
by 528 observers in an area that spans Calgary to Winnipeg and up north to Humboldt
(as a ‘line’ running east to west). Monarchs can fly over 100 miles in a
single day, with the right conditions, by coasting on air currents. They often
fly at 800 to 1,200 feet high, where you can’t see them. Monarchs know where to go. Scientists believe
they use the sun’s position and Earth’s magnetic field to navigate
directionally.
Luring
a monarch to your yard requires nectar plants like blazing stars (Liatris),
goldenrods (Solidago spp), asters (Symphyotrichum spp),
coneflowers (Echinacea spp), bee balm (Monarda spp), and Joe-Pye weed (Eutrochium
purpureum). However, a host plant is required for a monarch to lay its eggs
on and available for the caterpillars to eat. Showy Milkweed (Asclepias
speciosa) is a tall plant with large pink-purple, sweet-smelling
star-shaped flower clusters, common in southern Alberta. The Low/Dwarf Milkweed
(Asclepias ovalifolia) is smaller (25 to 60 cm) with white to light pink
flowers. All are native plants found in sunny, dry areas in dry fields, rocky
areas, and along roadsides. Less common is the Green Milkweed (Asclepias
viridflora). Check out local native plant breeders for seeds and plugs. You
will have great xeriscaping plants for your garden.
It
is important to note that milkweed contains toxins, so caution should be taken
if planting in areas with pets or livestock. How monarchs find their way is a
huge topic, but more than one milkweed plant is needed to lay eggs and feed
their caterpillars. Find a neighbour that is interested in monarchs and create
a milkweed corridor!
While
the monarch rules in North America for its long-distance migration, do check
out the painted lady – Vanessa cardui -which rules! Across the Atlantic,
its southern stop is the South Sahara, and it can end up at the Arctic Circle,
taking up to 10 generations to complete some 10,000 km and flying across
oceans.
Contact
Monika at [email protected] for more information or topics!
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