Monarchs (Danaus plexippus) are not dragonflies, but they are fascinating insects. These migratory butterflies have an incredible life cycle, which can be found at the Monarch Watch website.
Since the eastern population of this species winters in Mexico, it takes a couple generations to make it to the northern US.
We don't see greater numbers in southeast Michigan until mid-summer, although the first individuals make it to our area as early as mid-May. Common Milkweed (Asclepias syriaca) doesn't get large until June, with flowering later in the month. This plant is one of the common host plants for the butterfly eggs and larvae. A generation or two may be produced in the northern US and southern Canada.
In our yard, we offer several host plants including: Common Milkweed, Butterfly Weed (A. tuberosa), Whorled Milkweed (A. verticillata), Swamp Milkweed (A. incarnata), and Tropical Milkweed (A. curassavica). Unlike the others, the latter is non-native and not hardy here, but we pick some up and grow it as an annual if we see it at a nursery. In any given year, we may have 10 to 30 caterpillars. We remove many and raise them in a small tent or enclosure for protection from predators or injury.
In late summer and fall, adults begin the couple thousand mile migration south towards the wintering grounds in Michoacan, Mexico.
Since the mid-1990s, I have tagged southbound migrating Monarchs. Some years I only find a few individuals and other years several dozen are tagged. The organization Monarch Watch sells the adhesive, paper tags which have unique ID numbers printed on them. On the right is a Monarch we tagged in our yard a couple years ago.
Earlier this year on a whim, I checked the tag recovery database. To my surprise, there was a recovery of one of my tags! LHA926 was a male we caught on 27 Aug 2008 in our yard in Dearborn. On 3 March 2009, this individual was recovered by Javier Martinez in Sierra Chincua, Michoacan, Mexico. (near N19 36 23 W100 14 30 ) The distance between the two locations is 1,858 miles (in a straight line).
This is the location of one of the Monarch santuaries, west of Mexico City. A detailed look at the sanctuary is here, at the web site of the Monarch Butterfly Fund, one of the partners (Monarch Watch is another) of the Monarch Joint Venture.
One never knows when data will be most useful. Some years we've tagged several dozen, but 2008 was one of the fall seasons when we didn't find many Monarchs. A total of only 12 were tagged, 2 were reared in our yard and the remainder were from multiple locations in SE MI. It's incredible that one of the twelve was refound that winter.
I'd encourage others to order tags from Monarch Watch since the fall migration season isn't far away.