Let’s help save the monarch butterfly
Story by Dorothy Dobbie. Butterfly cluster by Kate Johnston. The declining numbers of the monarch butterfly should be
of concern to all who love wildlife and gardens and the way the intrepid monarch animates our favourite spaces. Here at the local gardener magazines, we and T & T Seeds have decided to do some- thing about their dwindling numbers. We are encouraging all our readers to plant milkweed. We will be happy to send you a FREE packet of milkweed (Asclepias tuberosa) seeds if you will send us a self-addressed, stamped envelope.
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ack in 1996, there were so many monarch butterflies overwintering in the Oyamel forest of central Mexico that the fir tree branches that harbored them buckled
and broke beneath their fluttering weight. They covered a massive 44.5 acres of forest. In 2013, the fir trees (Abies religiosa) of the Oyamel were
under no threat from butterflies. The monarch population had dropped so drastically that only 1.65 acres were occupied by the returning butterflies. Over the past twenty years of counting the butterflies,
populations have fluctuated, but there seems to be a down- ward trend now that is causing concern for everyone from scientists to children who miss their cheery presence in the garden. Who or what is to blame? It appears to be a combination of
weather-related events and man-made practices. Drought in Texas and other parts of the U.S. has had a negative impact. A very cold spring last year is probably responsible for some of the loss. Monarch butterflies are very cold sensitive and
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cannot fly at temperatures under 13°C (55°F). Their flight muscles seize up in cold weather. At the human responsibility level, the practice of logging in
the park has reduced the coniferous forest. The butterflies that migrate to Eastern Canada roost under the fir tree’s shelter- ing branches to avoid rain and cold winds. As the forest thins, protection from the elements is reduced and more butterflies die. Tourism is also taking a toll. At the Monarch Biosphere Rescue Park, as many as 24 buses often line up in the parking lot despite a sign that limits visitors to 20 at one time. But the biggest problem facing the migration is lack of milk-
weed along their migratory flight paths. Agricultural prac- tices that induce farmers to plant genetically modified crops have decimated this once plentiful native plant, the only plant upon which the monarch will lay its eggs and the only food the emerging caterpillars can eat. Monsanto has developed seed that is resistant to glyphosate,
sold under the name of Round Up. Unfortunately, milkweed is a collateral casualty when farmers spray their crops. In Iowa 98 per cent of the milkweed has been eliminated. Milkweed is critical to monarch butterflies not only as a food
source for their caterpillars, but because it equips the butterflies with a means of self-defense by providing them with a build-up of cardiac glycosides, which is poisonous to many of their preda- tors, including birds.
The migration
Most monarch butterflies in their final adult stage have a brief but glorious lifespan of two to six weeks depending where
Early Spring 2014 • 17
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