The monarch is among the most easily recognized insects in Canada, its wings a deep orange laced with dark veins and edged with a border of white flecks. Each summer the butterflies fan out across the southern provinces, and nowhere do they gather in greater numbers than the meadows of southern Ontario. What sets the monarch apart from nearly every other insect is the vast journey it undertakes: no other butterfly on the continent travels anything like so far, crossing thousands of kilometres between its summer haunts and a distant wintering ground.
The survival of the monarch rests almost wholly on a single plant. The female lays her eggs only on milkweed, and the caterpillars that hatch will feed on nothing else. Milkweed carries a bitter poison, and as the caterpillars eat they store that poison in their own bodies without coming to harm. The chemical stays with them into adulthood, so that a bird which tries to swallow a monarch meets a foul taste and seldom repeats the error. In this roundabout way, the plant that nourishes the insect also defends it.
