The amazing monarch!
Outweighed by a penny and powered by wings no wider than a toddler’s hand, the iconic monarch (Danaus plexippus) is right now embarking on the first stage of a migration that will cover upwards of 3000 miles, with some individuals traveling over 200 miles in a single day! They will wind their way across mountains, deserts, and cities, through multiple seasons and weather extremes, in a round-trip effort that will span five generations.
Monarchs in the United States are split into two populations, one east of the Rockies and the other west, along the Pacific Coast. The western monarchs spend their winter in California. Those to the east winter in the mountainous oyamel fir forests of southern Mexico.
It’s now in early spring when the eastern monarchs descend from the oyamel firs and move northward through Texas, allowing us to re-appreciate their beauty and marvel at their incredible stamina, navigational abilities, and the unique spectacle that is the monarch migration.
An epic journey
As temperatures warm and days lengthen, monarchs finish their development which was suspended over the winter, become reproductive and begin mating with fervor. Once mating completes, around February and March, the females leave the males behind in Mexico and head for the milkweed that is now sprouting across Texas.
And so the migration back to the United States and Canada begins.
The energy expended to complete this first leg of the journey is tremendous. After six weeks or so, now March and April, the female monarchs must find a milkweed leaf on which to deposit their eggs before they die. Once laid, four days will pass before the eggs hatch into voracious eating machines – baby monarch caterpillars.
Monarch caterpillars feast night and day on the leaves of their host plant and, incredibly, will gain 200 times their body weight in just two weeks. When the feasting ends they form their chrysalis and spend the next 10 days metamorphosing into an adult butterfly, vibrating with color and ready to renew the march north. This is generation 1, the offspring of the butterflies that overwintered in Mexico.
Several more generations will live and die over the summer, travelling further afield, but just one generation will make the entire journey back to the oyamel firs beginning in October.
The fall migration is even more dramatic than the spring, after reproduction has bolstered the population, dozens and even hundreds can be spotted hourly.
Creating safe havens for pollinators in our yards and communities provides vital waystations during spring and fall migrations.
The migration in crisis
Once 700 million strong, monarch populations have now crashed. It’s estimated the eastern population has plummeted by more than 85% while the western population is suffering even more – only 28,000 were counted this winter. Multiple issues are to blame:
Habitat loss and fragmentation. Over 160 million acres of monarch habitat has been lost to development since 1996. Illegal logging of the overwintering sites in Mexico is also taking a toll.
Climate change. The increased frequency and intensity of extreme weather events can devastate migrating populations. Because of the incredible density of monarchs in the overwintering grounds, severe freezes there are catastrophic.
Pesticides and herbicides. Milkweed used to grow throughout corn and soybean crops across the south and midwest. But herbicides have driven milkweed to near extinction in these agricultural landscapes and depleted monarch populations along the way. Monarchs are also being impacted by neonicotinoids, a new class of insecticides that spread their toxins through the plant’s tissues. Caterpillars that dine on these plants quickly perish.
OE. Ophryocystis elektroscirrha (OE) is a parasite that infects monarchs, causing them to die in the pupal stage or emerge deformed. Milder infections result in shorter life spans and an inability to fly properly. OE pervades in our area as non-native tropical milkweed (Asclepias curassavica) continues to grow through the cooler months, after native milkweeds have died back. Follow these important steps if you choose to grow tropical milkweed.
Monarchs overwintering in the oyamel fir forest of Mexico
What You Can Do
Join The Woodlands Township Plant for Pollinators Program. Through this program you can…
- Get notified of upcoming lectures, classes and workshops by signing up for the Township’s Environmental Services blog and calendar updates. These free events focus on pollinators, native plants, invasives removal, organic gardening, no-chemical pest control and more.
- Ask for a presentation on the Plant for Pollinators program and how to create habitat from the Township’s team of Environmental Education Specialists.
- Follow the monarch migration with Journey North, check out the Pollinator Partnership’s Million Garden Challenge and more with these partner links.
- Volunteers are needed for larger community planting projects. Help to weed, seed and spread habitat for all types of pollinators. Contact firstname.lastname@example.org if you or your group can lend a hand.
- Download the easy-to-use iNaturalist app on your phone and monitor your habitat for monarchs and other pollinators. Your findings will support the Plant for Pollinators Project. It’s also a great way to learn more about nature!