The monarch butterfly is noted
for its bright colours, 76 to 102 mm (three to four inch) wingspan,
fondness for flowers and wide distribution. The monarch is the only North
American butterfly that migrates north and south on a regular basis. One
of the few milkweed butterflies found in North America, female monarchs
lay their eggs on the underside of wilkweed leaves. The larvae feed upon
the plant's somewhat toxic sap; as a result, the larvae retain this
toxicity in their bodies, and predators learn to avoid eating them because
they «taste bad».
Monarchs west of the Rockies winter in California. Monarchs from east
of the Rockies begin their migration to Mexico in mid-September to
October, and travel in a slow-moving loose or compact swarm. Dr. Fred A.
Urquhart, a Canadian, discovered that in a small area in the Sierra Madre
Mountains west of Mexico City, monarchs gather by the millions- perhaps
100 million in all. One of his tagged specimens had flown an amazing
2,020 kilometres to Mexico from Chaska, Minnesota.
While in Mexico, the monarch butterfly remains in a sluggish state, as
the cool weather reduces its metabolic rate so its body maintains the
nutrients needed for the return flight northward. While one generation
accomplishes the southern journey, it way take three or four generations
to return to the original range, arriving in May or early June.
Butterflies North and South
Monarch Watch
Florida Monarch Butterfly Website (The)
Journey North
David W. Allard
Monarchs, Viceroys and Queens
Point Lobos State Reserve
Mrs. Baston's Kindergarten Monarch
Texas State Insect (The)
79th Street Boat Basin Flora and Fauna Society
Butterflies of North America
University of Michigan
Enchanted Learning
San Diego Natural History Museum
Butterflies of Hawaii
Herbison-Evans & Crossley
CyberScol (french)
Canadian Museum of Nature (french)
Toile des insectes du Québec
Insectia.com (french)
Mario Maier (deutch)
