A Lepido-what? And why does this milk-sucking involve heavenly change? Well, since you asked, it describes the incredible life journey of the monarch butterfly.
Imagine weighing less than 1/1000th of an ounce, having paper-thin wings to fly thousands of miles to your mountainous winter home, and depending upon one poisonous weed in order to survive. This is a miracle of Mother Nature and the insect Order Lepidoptera that includes the butterflies and moths.
The vivid orange and black markings of the monarch butterfly are recognized by most people but you may not know about its intriguing metamorphosis from microscopic larvae to full-sized adult in about a month. Male and female monarchs are distinguishable. Females have darker veins on the wings and males have a dark spot in the center of each hindwing.
The life cycle begins when a female monarch lays hundreds of creamy white tiny eggs on the underside of milkweed leaves, usually one egg per plant. The caterpillar emerges a few days later to begin two weeks of voraciously eating nothing but milkweed leaves and sheds its skin (four times) as it grows. At about 2 inches long and weighing 3,000 times more than at emergence, it sheds its skin one final time and enters the pupal stage as a jade green chrysalis. Inside the chrysalis, the transformation from crawling insect to elegant flying beauty occurs over a two-week period.
The life span of a monarch varies from a few weeks to a few months, depending upon the time of year. Shorter days and cooler temperatures in mid-August trigger hormonal changes. Instead of mating, monarchs begin the journey south to the mountains of Mexico, a journey of 1650 miles from Clinton. West of the Rockies, monarchs migrate to the southern Pacific Coast of California. Monarchs migrate about 50 miles per day but some have flown up to 80 miles.
Millions of monarchs spend the winter on fir and pine trees, until warmer days in March signal them to return northward. They mate, fly perhaps as far as Texas or Oklahoma, lay their eggs and die. Newly hatched monarchs fly farther north (as far as Canada) and create successive generations, until the great-grandchildren of the ones that overwintered in Mexico begin their migratory trek a year later.
Milkweed contains a poison that helps protect the monarch’s egg by deterring feeding by leaf eating insects such as grasshopper. As the monarch caterpillars eat the poisonous plant, they become poisonous. The butterfly’s bright colors advertise they are not good to eat, although spiders, reptiles and certain mammals and birds can eat them without ill effect. The poison also adds a foul taste to deter predators.
The drastic decline of monarchs is attributed to several factors (pesticides, weather, habitat loss) but the disappearance of milkweed from the landscape is most significant. The potential listing of the monarch as a federally threatened or endangered species has created a national interest in restoring milkweed and monarch populations. There is great concern that if monarchs were federally listed, it would impact agricultural operations as well as any other landscape scale projects where pesticides are applied or mechanical disturbance of potential butterfly habitat is required.
Monarch tagging has become a popular international conservation project since it first began in the 1960s. Tagging has revealed some of the mysteries of monarch migration. The next monarch that you see may be one of the long distance fliers migrating its way south to a warm winter retreat.
Ed Britton is a wildlife Refuge manager at the Upper Mississippi River National Wildlife and Fish Refuge and a volunteer at the Bickelhaupt Arboretum in Clinton.