Introducing-Monarch Butterflies

Students who live across North America where monarch butterflies are found can participate in an international science experiment this spring. By simply reporting the sighting of their first monarch butterfly, they will help generate a "live" map of monarch migration across North America. This has never been done before! The map might show how migration is related to daylength, temperature and the growth of the plant food on which monarch caterpillars depend--milkweed.

• The scientific name for these subtropical butterflies is "Danaus plexippus".
• They mostly winter in central Mexico because of the warmer climate and tall fir trees. Some winter along the western coast of California.
• Thousands rest on one tree trunk, pasted to each other while hibernating.
• They nest at elevations of 9,500 to 11,000 feet where the air is just the right temperature for the more than 65,000,000 individuals!
• 80% of the Monarch colonies have lost their habitats from development so far, and within 10 to 20 years they could become extinct (in eastern North America).
• Most Monarchs migrate, but some do not.
• During the spring and summer they seek milkweek and travel north into Canada, from their Mexican wintering grounds
• Migration is difficult because of the constant destruction of their habitats.

• Migrating Monarchs stop for the night and cover branches of trees.
• They are attracted to yellow because of the color. Some believe it is magnetic to them.
• These milkweed lovers use most of their energy in flight and few survive the trip because it is so long.
• Smoke and spring fires cause frenzied flight and takes them off course.
• They like to cluster together in a tree like a feather duster.

• These Halloween-colored butterflies are constantly in search of milkweed.
• Larvae feed on milkweed plants and adults drink wild flower nectar.
• Milkweed contains poisons that protect the Monarchs from (some) insect and bird predators. Birds have been known to vomit if they eat a Monarch butterfly.

• Males search for females and both search for milkweed.
• Mating usually occurs in the afternoon and the pair flies together joined for as much as an hour.
• Most Monarchs mate just before migrating north. It is mostly fertilized females that migrate north.
• Females lay one egg at a time on a milkweed plant, being careful not to stress the plant. The young eat any eggs they find on the milkweed.
• Milkweed poisons are transfered as is from the larva through the pupa into the adult for protection.
• Most generations live about three weeks, but others (of the over-wintering generation) live longer.

• They winter together in 38 permanent wintering areas of California and about 12 small sites in the Mexican mountains west of Mexico City.
• When flying during low temperatures, they fly low to warm ground which can puts them in danger from mice.
• They travel north only as far as the milkweed varieties grow in order to exploit that food source.
• These brightly-colored insects convert the milkweed poison into a chemical weapon for their own defenses.
• These butterflies cluster together in a cold, moist winter environment to survive in a sexually inactive state. (Thus, entire populations depend on small areas in their wintering grounds.)
• To conserve energy, they hitch rides on spirals of warm air called "thermals" just as the hawks do when they migrate.
• They store fat in their bodies to last them through the winter as long as they stay fairly inactive.

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