Door to Nature

The sequence of photos depicts the life cycle from caterpillar to butterfly. Photos by Roy Lukes.

There is one, among the myriad of wildlife species in Door County, which has come to be one of our favorite natural symbols of summer, the Monarch Butterfly. The 45 summers that I have admired, watched, and fed some of them have brought ups and downs in their numbers with this summer being one of the lowest. Freezing weather on their wintering grounds at around 10,000 feet elevation in the Oyamel Fir forests west of Mexico City, coupled with several consecutive droughty summers in our region surely are included in the natural forces with which they must contend and which control their population.

The relatively few Monarchs that arrived here in early June were first generation butterflies of a pair that had spent the previous roughly four to five months in Mexico. Assuming that the pair may have left Door County in mid-September of last year, they were the last of three or four generations to have existed here. The first two or three generations successfully bred, the females laid many eggs and then both male and female adults died after living from two to six weeks.

Amazingly, the last generation of Monarchs to eclose (a better term to use rather than emerge) had sexual organs which were immature. This last generation of strong fliers headed south using what modern science believes to be a built-in time-compensated sun compass to a centuries-old Monarch wintering site containing around 50 square miles. Bear in mind that at least four generations have passed and that they were quite magically locating a place to which they had never been to before, but to where their great-great-great-great grandparents had been the previous winter.

There they wintered, gradually matured sexually, started northward sometime in March, mated, laid eggs on one of several species of milkweed plants in, for example, southern Texas or Louisiana, and then these seven-month-old butterflies died. The eggs hatched into caterpillars after around four days followed by about 14 days of feasting on milkweed foliage. Now they shed their skin and developed into beautiful jade-green chrysalids where they remained for approximately 10 days. Upon eclosing as adults they headed north arriving in Door County anywhere from late May to mid-June.

I remember as a child seeing some Monarchs in our large flower gardens at home in Kewaunee but I don’t recall any native milkweed plants near our place. The only native species there are the Common Milkweed, Asclepias syriaca (as-KLEE-pea-as si-RHY-i-ca) and the Swamp Milkweed, A. incarnata (in-car-NAY-ta) on which those adults would have been feeding when they were in their larval stage. Either the adults in our garden were feasting on the nectar of various flowers or weeds or the males were pursuing females for mating.

Our front yard now is ablaze with colorful flowers, some perennials but mostly annuals, all of which are attractive especially to butterflies and hummingbirds. The tall Zinnias rank number one in attracting the butterflies as well as supplying them with copious amounts of nectar. The tall species of Mexican Sunflower comes in second while the gangly, sparkly, purplish, tall Verbenas rank a close third.

The two host plant species which have been virtual magnets to the female Monarchs again, and on which they have laid some of their eggs, are: (1) the tall native Swamp Milkweed, whose species name of “incarnata” means flesh-colored, and (2) the Mexican Milkweed, Asclepias curassavica (cur-a-SAV-i-ca). I’ve also heard this flower called the Bloodflower and the Scarlet Milkweed. It is strictly an annual at our latitude, is easy to grow from seed and the Monarchs favor it quite highly. I counted a minimum of 12 Monarch caterpillars on the eight Mexican Milkweed and the one Swamp Milkweed plants a few days ago.

Another excellent host plant for attracting the Monarch females and upon which they will deposit their eggs is the Giant Swan Plant, or simply the Swan Plant. We did not get any of these plants this year but hope to next spring. A very good source for seeds of several species of Monarch Butterfly host plants is the “Monarch Watch” organization. Their website is http://www.Monarchwatch.org, and their phone number for seed orders is 1-800-780-9986. This non-profit group, dedicated to education, conservation and research, ranks very high in my book!

Dr. Karen Oberhauser, who has been studying the Monarchs for over 25 years and is one of the founders of this group, has, along with Ms. Rea and Mr. Quinn, written an outstanding little book, Milkweeds, Monarchs and More, a Field Guide to the Invertebrate Community in the Milkweed Patch. Its colored photos are excellent and I refer to this little gem of a field guide a lot.

The 4’x 8’ raised bed in our front yard, in which we plant all of our milkweed plants along with other butterfly and hummingbird-attracting plants is what the “Monarch Watch” group promotes and calls a Monarch way station. It provides these incredible butterflies with nectar on their way north, both nectar and their larval host-food plants throughout the summer, and finally more energy-rich nectar for the monarchs as they stop to feed along their fall migration to Mexico. What a highly precarious balance exists between our needs and the needs of other species with which we share the planet. Many require our help.

We hope that these wonderful creatures are having a good summer in this region and that next spring their progeny will return in greater numbers to provide nature lovers with more exciting observations. Summer would be very incomplete without Monarch Butterflies.