Update: Monarch Butterfly Migration Late Summer 2010
Dear Gardening Friends,
So many have telephoned or emailed inquiring about the status of the annual Monarch butterfly migration through our region. This past summer I have observed umpteen Monarch butterflies and caterpillars in cultivated gardens, wildflower meadows, and along the shoreline; however, I did not see the great numbers in great heaps roosting in any one particular place that I have in some years past. Rather I would find a small passel here and a small passel there—perhaps several dozen at a time—roosting in the wild black cherry trees (Prunus serotina) at Eastern Point, awakening in the early morning and nectaring at the Seaside Goldenrod in the meadow below.
Although the Monarchs are guided genetically, using their internal sun-compass navigation and circadian clock, each year the annual southward migration takes a different form that depends on many variables, primarily the weather conditions in their overwintering site in Michoacán, Mexico as well as weather patterns in their US and Canadian breeding grounds. Because Cape Ann is located at approximately 43 degrees latitude north, our peak migration pattern is estimated at around September 11, but I modify this pattern because of the strong winds and storms we often experience in the late summer living along the coastline.
I have read reports of fantastic migrations that are taking place this year, from Long Island, south to Cape May, and west to Virginia—some saying it is the best they have seen in decades! I continue to remain on the look out because the air temperatures were atypically warmer this summer, creating a longer breeding season than usual, which would indicate that there may be newly emerging Monarchs on the scene. While photographing during this year’s migration, I encountered a pair of Monarchs mating, a very unusual occurrence at this time of year. The “Methuselah” Monarchs that we see in late summer and early autumn are generally speaking sexually immature and do not mate until next year, after they journey south and after they overwinter and awaken in Mexico.
Monarchs observed in late summer and early autumn are intent on nectaring and not easily distracted. This later generation of Methuselah Monarchs is feeding aggressively to increase and store their lipid reserves for the long journey south. We provide plenty of nectar-rich blossoms to help the Monarchs in their exhaustive migration, taking cues from marsh and meadow. Blooming freely at this time of year are copious members of the Composite family—goldenrods, asters, pearly everlasting, zinnias, ironweed, Mexican sunflowers, and Korean daisies. If one diligently deadheads the butterfly bushes and Verbena bonariences, they too will be available for the migrating Monarchs.
My favorite goldenrod is Seaside Goldenrod (Solidago sempervirens), which blooms from August to November. Seaside Goldenrod is the gorgeous brilliant golden wildflower we see growing and glowing along the edge of the sea. It is easily differentiated from other New England goldenrods in that the flowerheads are comparatively larger and the leaves are thicker and fleshier, with a waxy feel, an adaptation to the drying effect of salty sea spray. Seaside Goldenrod grows prolifically in rich, moisture retentive soil, less so in drier conditions.
Although I strongly discourage digging plants from local marsh and meadow, perfectly acceptable is the practice of collecting ripened seed stalks and shaking them about. That is just how we obtained our Smooth Asters (Aster laevis). With cheery one-inch button-shaped flowers borne along the lengths of the stalks, the pale-hued lavender-blue ray flowers and yellow disk florets of Smooth Asters are attractive to bees and butterflies. We have observed Common Sulphers, Pink-fringed Sulphurs, Monarchs, American Ladies, Red Admirals, and Cabbage Whites nectaring simultaneously on a clump growing in the sheltered border along our fragrant path. Pinch back the developing growth tips during the early part of the growing season (until roughly July fourth) to encourage a bushier and more compact plant. Asters provides nourishing sustenance for transitory butterflies when many nectar-rich plants have finished blooming for the season. Not particularly fussy in regard to soil conditions, Smooth Aster grows and flowers profusely in full sun to light shade. Smooth Aster and Purple-stemmed Aster (Aster puniceus) are the asters we see blooming along the backshore at this time of year. With golden yellow florets at the center of their ray flowers, asters and goldenrods create a convenient landing pad for nectaring Lepidoptera. Flowering alongside ripening red berries and surrounded by changing autumnal leaf color, goldenrods and asters transform the seasonal tapestry.