The Tropical Butterfly House was and still is my favorite part of Seattle’s Pacific Science Center. This warm and humid part of the center is home to many different kinds of butterflies but many kinds of butterflies call the Pacific Northwest home outside of the Butterfly House! Monarch butterflies are just one of the butterfly species that call the Pacific Northwest home for part of the year but these beautiful insects are facing extinction because of human-caused climate change and changes to habitats.
Monarch butterflies are herbivores with a wingspan of 3.7 to 4.1 inches and lifespan of 6-8 months. Starting life as larvae, these invertebrates eventually become colorful caterpillars before entering the pupa stage and creating a hard protective case around themselves. Monarch caterpillars are striped with yellow, white, and black bands and can get to be 2 inches in length! After some time, they emerge as beautiful butterflies with easily identifiable black, orange, and white colors.
Milkweed and Other Plants
Milkweed plays an important part in a monarch butterfly’s life. This plant provides glycoside toxins to the butterfly, which deters other animals from eating them. Most animals won’t die from eating a monarch butterfly but will get sick enough to not try again! Plus, the toxins made the butterflies taste really bad. The milkweed is eaten by monarch caterpillars and the relevant toxins are stored in their system well into adulthood. As adult butterflies, monarchs will feed on nectar from a range of native plants, including milkweed.
Migration and Habitat
These butterflies are some of the easiest to identify because of their coloring and they are found all across North America. There are two populations here that are separated by the Rocky Mountains and their presence in a certain area will depend largely on the time of year, as they are one of the few migratory insects!
On the west coast, monarch butterflies can be found as far north as southern Canada and will migrate to coastal California to spend the winter. The eastern population spends winters in the cool, high mountains of central Mexico and summers east of the Rocky Mountains. A small number of these butterflies can be found here in the Pacific Northwest during the summer.
- Monarchs Ride West Coast Winds: Proof of Butterfly Migration by Scott Weybright, WSU College of Agricultural, Human, and Natural Resource Sciences
It takes several generations of these butterflies to make the migration possible, especially for those who live east of the Rocky Mountains. But some scientists believe that monarchs have been migrating all across North America for thousands of years. Every year, large populations of these insects will travel thousands of miles and habitat loss in the US and Mexico has taken a huge toll. Additionally, many people have fought against a border wall between those two countries in part because of the effect it’ll have on monarch butterflies, other animals, and the delicate ecosystem along the border. The Rio Grande, for example, is one such ecosystem that will be affected.
- Butterfly Preserve on the Border Threatened by Trump’s Wall by Claire Harbage, KNPR/Nevada Public Radio
There are some monarch butterfly populations in places like Hawaii, Puerto Rico, some islands of the Caribbean, and New Zealand. These populations were likely introduced by humans or naturally dispersed there by storms. They are not a part of the annual migration that North American monarchs partake in.
Helping Monarch Butterflies
There is a lot that individuals and society at large can do to help monarch butterflies, as we are quickly losing monarchs. Planting bee/butterfly friendly gardens with lots of native plants (including different kinds of milkweed) can definitely help. Fighting against climate change (including using fewer fossil fuels, reusing materials like clothes and plastic, and recycling) helps the planet and animals/insects of all kinds. Some individual changes can help but advocating for green legislation and against corporate greed makes a huge difference too. If you’d like more ideas, the US Fish and Wildlife Service has resources on how to help save the monarch butterflies.