These are migrating Monarch [Danaus plexippus] on Giant Blue Hyssop ...
Scientific Name: Agastache 'Blue Fortune' ...
Family: Lamiaceae ...
This shot was taken two years back in the Lurie Garden, Millennium Park ... on August 30, 2006 .. It was a beauty to see so many butterflies together ... In the image below we can spot about six butterflies ...
Click on the image for enlarged view ...
Chicago happens to be in the path of migrating monarchs ...
While most butterflies have a very short life-span, average of two weeks to one month ... some butterflies like Monarchs may live to about 9-10 months ...
However not all Monarchs generations live for 9 month ... They have a very complex life-cycle ... with different generation serving different functions. Like during the spring and summer months, the Monarchs that we see in US and Canada, live for only about a month ... Only the caterpillar that develop into Monarchs in late summer, will be the "migrating generation" and survive for about 9-10 months ...
The fall in temperature and shorter days, is believed to be the trigger for migration ... The Monarchs migrate about 4500 kms / 2800 miles in about 6 weeks. Monarchs along the west coast winter in California and along the east coast winter in Mexico ... But they do not reproduce until spring ... Only by Febuary/March they reproduce and die off [so this "migrating generation" lives the longest life] ... The next generation begins migrating north in summer months ... These generations live for only about one month ... After 2-3 generations reach Canada ... and then again the reverse journey from Canada to California / Mexico begins ...
