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Monarch Butterflies

Monarch Butterflies

The Monarch butterfly, scientifically known as Danaus plexippus, is a beautiful orange-and-black butterfly that captures our imaginations, much scientific curiosity and can use our conservation. Its caterpillars feed on Asclepias genus plants and a few others in the milkweed plant family. To survive, the Eastern US and Canadian Monarch populations must make a migration journey of several thousand miles, taking up to four generations to complete.  There are several other migratory and non-migratory monarch populations worldwide, including one in the Western US.  Danaus plexippus is not an endangered butterfly, but its North American migration may be in danger of disappearing.

The Museum supports the monarch’s life cycle by planting and maintaining many native nectar plants and several species of milkweeds throughout its public exhibits, garden beds and behind-the-scenes grounds.  VLM has been a certified Monarch Waystation through Monarch Watch since 2005.

Museum staff and volunteers have reared the migrating generation of Monarch butterflies since 1988 and have tagged and released over 1400 migrating adults since 1996.


You can follow the monarch migration on two web sites:

Watch a monarch emerge from its chrysalis:

Monarch Tagging

Monarch Watch tags are about 1/4 inch round, made of weather-proofed paper with a strong adhesive. Each has a unique letter and number code plus Monarch Watch contact information printed on them. Scientist and citizen taggers gently capture and hold monarchs, place a tag on the lower side of a hind wing and release them unharmed. The tagger records the tag code, date and location tagged, and then sends in the tag data sheet to Monarch Watch at the end of the tagging season. If the butterfly is later found and its tag reported, Monarch Watch can let taggers know when and where their butterflies were recovered. The butterflies can’t be tracked in “real time” yet.

Monarch Migration

Even with over 50 years of tagging data, monarch mysteries remain. How do Monarchs find the Mexican mountaintop sites each year when they are several generations descended from last year’s overwintering insects? What clues and senses do they use to navigate to Mexico, especially when they are blown off course?

Their journey to Mexico is like a 6-foot-tall human circling the globe 11 times in a row!

For Peninsula monarchs, migration can begin in mid-September [when other local monarchs are still breeding], then peaks in late September or early October and most are gone by October 20th. Eastern US Monarchs arrive in Mexico beginning in early November and into December.

The monarch overwintering population in Mexico has decreased by more than 80% over the past 20 years.  Scientists have hypothesized that the continuing decline in migrating monarchs may be due to deforestation in Mexico, extreme climate fluctuations in North America and the increase in herbicide-based agriculture destroying crucial milkweed habitat in the Midwest.

Three butterflies tagged by the Museum have been recovered along the migration route. One butterfly was found in Mexico in February 2001. Another monarch was recovered locally in Newport News in fall 2001. The third monarch was photographed in a butterfly garden in Austin, Texas on October 25, 2008. It was found by a six-year-old boy doing a science project on migration. The monarch (shown here) had traveled at least 1,306 miles in the 22 days since it had been released by the VLM.

Neat Monarch Migration Stats

  • Monarch butterflies are 1.25 inches long, weigh less than a paper clip, and fly on paper-thin wings up to 2858 miles [4600 km] to Mexico.
  • The furthest journey recorded of a tagged monarch butterfly was about 2750 miles from Grand Manan Island, Bay of Fundy, New Brunswick, Canada to Mexico.
  • Monarch migrants move 10 to 15 miles per hour for 6 to 8 hours per day, depending on wind speed, average 44 miles per day but can move up to 200 miles per day.
  • Glider pilots have seen monarchs as high as 11,000 feet above the ground.
  • Radar has picked up monarchs flying as high as 5000 feet off the ground.
  • Monarchs can’t fly below temperatures of 57°F (unless they bask in the sun or shiver to warm their flight muscles).
  • It’s been estimated from tagging studies that 25-50% of monarchs survive the fall migration.
  • Migrants from the northern US and southern Canada take 8-10 weeks to reach the Mexican overwintering sites, while those from further south take 4-6 weeks.

How Can I Help Conserve Monarch Butterflies?

Plant milkweeds and nectar plants in your yard. This creates food and a nursery for the summer generations and a “fast food” stop for migrating monarchs. For more information on certifying your yard as a Monarch Waystation, go to go to Plants suitable for a Monarch Waystation are sold at the Museum’s spring and fall plant sales (the last two weekends of April and September).

If you find a tagged live monarch, CONGRATULATIONS! Your options: catch it carefully or photograph the tag. If you catch it, write down all the tag information, the date and time you caught it, leave the tag on the butterfly and let it go. If you photograph it, get the complete tag information from the photo. Contact Monarch Watch using the information on the tag and leave them the tag letter/number code, your contact information and the date, time and location you caught it.  If you find a dead tagged monarch, gather and send the same information from the tag as for a live monarch.  If the person who tagged the butterfly turned in their data sheets then Monarch Watch will be able to give you information on where it came from. These “citizen science” data help piece together how a monarch makes its long journey to Mexico.

Links for Teachers

Information on Attracting Monarchs and Other Butterflies to Your Yard: