Gardening for Wildlife â

Danaus plexippus

As spring turns into summer the glint of sunshine on gossamer wings of orange and black heralds the return of the monarch butterfly. Although considered a mid-sized butterfly, the monarch is one of the largest of Canada's native butterflies. Fascinating to watch, this striking creature is renowned for its incredible migration. No other butterfly has the ability to travel thousands of kilometers each year.

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Each fall, monarch butterflies from throughout North America are drawn to a few isolated forests in the mountainous valleys of central Mexico and southern United States. In the cool, moist surroundings of these winter havens, the travel-worn butterflies rest throughout the winter months. After mating in the spring, they undertake the long trek northward. Most of them will not reach Canada. Females, laden with sperm, lay eggs on milkweed plants along the way, with the resulting offspring continuing the journey north. The butterflies that finally reach the northern limits in June or July probably hatched from eggs laid earlier that year. They are the third or fourth generation descendants of the butterflies that left the previous fall. After spending a summer feeding on nectar and laying eggs, these butterflies begin the return trip south in August and September.

Monarchs, though small and light, can reach speeds of two km/hour in still air and can average as much as 50 kilometres in a day. They are able to do this by taking advantage of rising air currents, allowing them to go high enough to ride with the wind. In opposing winds, they rarely venture out. Instead, they will mass in trees waiting patiently for more favourable conditions.

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photo: US Department for Fish & Wildlife	Â

Monarchs go through complete metamorphosis in four stages. First, the egg is laid on a milkweed plant. From this a caterpillar (larva) hatches. This eating machine eventually makes a cocoon, or chrysalis, and enters the pupa stage. Inside this smooth case, the pupa undergoes a wonderful transformation and an adult butterfly emerges.

Monarch caterpillars and adult butterflies have striking features and are, therefore, easy to spot. The caterpillars grow up to 2" long and are ringed with black, white, and yellow. They go on to form a chrysalis of pale green with gold markings. The adults have bright orange wings with prominent black veins, bordered by jet-black margins with rows of white spots. The undersides of their wings are paler and their black bodies have white spotting. Males differ from females in that they have a "stigmata," a patch of black scales, on the inside surface of their hind wings.