Feature Article February 19, 2004
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Milkweeds and Monarchs
As I look across a neighbouring fallow field, the snow is almost deep enough to hide them - the remaining stems of the Common Milkweed plants that bloomed profusely last summer. After the blooms disappeared the seed pods developed. Most of the pods burst open before the snows arrived, and all that is left at the top of the few stems still stretched above the snow are empty pods.
There may have been many flowers in the cluster of flowers on a plant, but usually only one or two pods will develop into a 7 to 10 cm. pod, which will split lengthwise to release its seeds. While the pods may release hundreds of seeds with long silky tufts of hair to be blown by the wind, the plant also spreads by its underground rooting system.
Common Milkweed, a member of the Asclepias family, is listed by the provincial government as a noxious weed. Other species of the family have been found highly toxic to livestock, and some evidence indicates that the Common Milkweed may, under some circumstances, also be toxic. The Asclepias family is named for Askeplios, the Greek god of medicine and healing, and there are over a hundred species in North America, but as far as I know, only two which live in eastern Ontario. Besides the Common, there is the Swamp Milkweed. Break a stem or leaf and it will exude a milky sap.
The toxin in the plants is due to certain alkaloids to be found in them. And this toxic fact is beneficial to one of the most striking of our butterflies - the Monarch. Larvae of the Monarchs feed exclusively on the leaves of the milkweed, ingesting the plants toxins, which are then found in their wings and exoskeletons, making both the larvae and adults poisonous to many predators. Because these chemicals also taste bad or can make the predator vomit, most learn to avoid both caterpillar and butterfly, recognizing them readily from their colouring. So the Monarch thrives where the Milkweed thrives.
Interestingly, the Viceroy Butterfly has evolved a colouring pattern very similar to that of the Monarch, and uses this as a camouflage ploy to protect itself from the same predators, even though it does not contain the same toxin or have the same bad taste.
So during the summer, in the field where milkweeds are found, you may see a number of the butterflies flitting over the field, lighting briefly on the milkweeds, and if you look closely you may find the caterpillar of the Monarch Butterfly or its jade chrysalis. The jade colour of the chrysalis will fade, and it will become transparent as inside its protective home, the butterfly develops and the colours darken until, in about two weeks, the caterpillar has transformed into the beautiful adult that emerges.
In late summer most of the butterflies will migrate. From Eastern Canada they may fly south to Florida, along the coast of Texas, or Mexico. In Mexico millions have been found resting in trees in certain areas. It was with sadness that I read a report a couple of weeks ago that 11 million had perished due to an unusual cold spell. I will watch to see how many return in the spring.
Observations: A Ruffed Grouse came to an untimely end when it crashed into a window at Helms in Oconto on January 21. Share your sightings - contact Jean at 268-2518; This email address is being protected from spambots. You need JavaScript enabled to view it.
