The Monarch Butterfly
There are few feats more gruelling in the natural kingdom than the mass migration of the Eastern Monarch Butterflies. Their impressive journey–one of the longest migrations of any insect– spans 3000 miles, from southern Canada all the way to their wintering ground, located amidst the soaring ranges of the Sierra Madre Mountains of Mexico. Come October, around 500,000 third or fourth generation Monarchs fly south, averaging 50-100 miles a day. The whole trip takes just under a month, right in time to commence Day of the Dead celebrations–where monarchs are believed to hold the spirits of the departed. There, they will roost temporarily in the lush foliage, passing time till their return migration the following spring.
On the return trip North, the butterflies do it in generations, laying eggs along the way like a relay of butterflies traveling back to Canada. Monarch populations face many obstacles. The biggest detriment to their populations is the lack of habitat –their native nectar sources, along with their host plant, the milkweed. Milkweed is the only host plant for monarch butterflies, and without an ample supply of milkweed along their migration route and in Canada, the butterflies cannot survive. The most impactful thing that humans can do to help the monarch butterfly is to increase their habitat. Planting milkweed and native nectar sources (Joe Pye, purple coneflower, etc) is the best way to increase the dwindling butterfly population.
Life Cycle – Egg to Butterfly in 30 Days
A female butterfly will deposit her eggs on milkweed leaves and flowers using a small amount of adhesive. After 3-5 days the egg darkens and the caterpillar becomes visible through the egg. The caterpillar will then munch its way out of the egg and then gobble up the remaining egg for nutrients. The monarch caterpillar goes through 5 instars before moving into the pre-pupation stage (11 to 18 days), devouring milkweed voraciously and molting between each instar. The pre-pupa stage lasts 12-24 hours where the monarch caterpillar first attaches itself by its silk to a carefully chosen, although sometimes precarious surface. This stage is also called the “J”, because of the way they hang, which looks just like the letter. It takes only a couple minutes to wriggle out of its skin and transform into the pupa (or chrysalis). Once in pupa form, it takes 24 to 48 hours for the chrysalis to harden. Finally, after another 8 to 14 days the butterfly becomes visible through the chrysalis and emerges (or ecloses) after 12 to 24 hours. Eclosing only takes a few minutes, the butterfly then hangs and allows their wings to fill with fluid from their abdomen, and after 4 hours of hanging and drying, the butterfly is ready to flutter away. An adult butterfly lives between 2 to 6 weeks (other than the migrators, who live 6 months), and females will lay 100 to 500 eggs, with a survival rate of about <5%.
Kallie Jackson
Procyon Wildlife Volunteer