Where Do Monarch Butterflies Migrate To?
Monarch butterflies happen to be one of the most loved butterflies and easily the most observed butterfly in North America. One amazing challenge of Monarch butterflies is that they have been making their annual migration to and from Mexico for as long as we can think of. However, not all Monarchs travel to and from Mexico. Some Monarchs travel to and from California. It all depends on where these amazing creatures are in North America. Unfortunately, in July 2022 Monarchs made their way on the Endangered Species List- not the type of list we want them on. Let’s talk all about where monarchs migration path is and what you can do to help.
What is so special about those Monarch Butterflies?
Monarch butterflies happen to be the only butterflies, that we know of, that can make the two-way migration to their overwintering sites in Mexico and California. They can travel an amazing distance, anywhere from 50-100 miles each day. But the really special part is that each Monarch is making a trip it has never taken before. According to the U.S. Forest Service, it will take 3-4 generations to reach the northern United States and Canada. That means that the Monarch butterfly that started the journey north will not be the one that reaches Canada or the northern United States. Monarchs are using their instincts to know where and when to go.
If Monarchs are making their route through the United States and Canada, they can travel up to 2,500 miles before their long journey is complete. One fact that I find fascinating is that Monarchs use air currents to help them travel those long distances. Warm air rises higher in the sky and cooler air sinks and is closer to the ground. Also, different air temperature can travel at different speeds. Warm air travels faster than cooler air. Monarch butterflies will use these different thermal air currents to help them get from one place to another. Definitely useful if you are traveling to such far off places.
by Ryan Hagerty
When does the Monarch Migration Begin?
In the fall, the Monarch migration begins around mid-August in the upper part of the United States and Canada and can last until the middle of November down in the southern part of Texas. In California, Monarchs will have their fall migration in October.
The spring Monarch migration begins in Mexico, for the eastern half of the U.S., in March for their journey to the north. For the Monarchs in California, the spring Monarch migration usually begins in late February.
For both the spring migration and the fall migration the Monarchs will begin their journey when the weather tells them to. These butterflies have an intuition that tells them when the time is right to begin their migration journey. Monarchs are what we call ectothermic, which means they are cold-blooded. The butterflies will need the sun to help them stay warm and keep their body temperature up.
Where do Monarch Butterflies Migrate To and From?
As I mentioned earlier, Monarch butterflies will roost in two different locations depending on where they are in the United States. Monarchs can not survive cold temperatures and must travel to places that are warmer and have a bit of humidity. If Monarchs are east of the Rocky Mountains they will journey south in the fall to the Oyamel fir forests in Central Mexico, located west of Mexico City. There are up to 14 different overwintering sites in Mexico for Monarchs to roost but these locations are dwindling due to over forestation at some of these sites. Some reports that I have read are saying that there are now only 11 or 12 different locations.
In locations that are west of the Rocky Mountains the Monarchs will migrate back to the California coast near San Diego and Santa Cruz, but they stay far enough inland so that they are protected from coastal winds and strong storms that can occur. They like to roost in Monterey Cypresses, Monterey Pines, and Eucalyptus trees. Monarchs like to pick trees that have an abundant canopy that will protect them, as well as locations that can maintain some humidity to help them conserve their energy while roosting.
Helping Monarch Butterflies
The best thing you can do for Monarchs to help during migration is to plant host plants and nectar plants. Host plants are plants that they lay their eggs on. The emerging larva will eat the host plant throughout the caterpillar stage up until they are ready to form a chrysalis. Nectar plants are plants that help the butterflies get nectar and will feed them when they are butterflies. These plants will be different from each other. The host plant is simple for the Monarchs- Milkweed (Asclepias).
Milkweed can be grown throughout the United States. However, not all milkweeds can be grown everywhere. Houston is one of the few locations that can grow Tropical Milkweed (Asclepias curassavica). On the other hand, Blunt-Leaf milkweed (Asclepias amplexicaulis), can be grown in much of the eastern portion of the United States. Showy milkweed (Asclepias speciosa) and Antelopehorns (Asclepias asperula) is grown mainly in the western portion of the United States. These are really beautiful milkweeds that I wish I could grow in Houston-but I can’t.
The nectar plants that Monarchs love most are lantanas, frostweed, goldenrod, Greg’s Mistflower, sage/salvia, sunflowers, groundsel, goldeneye, and Echinacea, to name a few. There are so many plants that serve nectar plants that I can’t name them all.
The National Wildlife Federation has a wonderful list of nectar plants for Monarchs.
Milkweed Controversy
I do want to mention that there is some controversy over if we should be growing tropical milkweed. I have personally been growing it for over 20 years and raising Monarchs successfully with it. However, I have seen in the last few years a small increase in the amount of Monarchs that are getting a parasite called O.E. (Ophryocystis elektroscirrha). I have also seen what we call “black death”. O.E. is a parasite that can cause adult Monarchs to come out of their chrysalis with deformed wings. Black Death is when the Monarch caterpillars become very still for a long period of time and then turn black and die. This is a result of a bacterial infection. Tropical milkweed has been linked to caring the bacteria that causes black death.
The Monarch Joint Venture has a great explanation of both O.E. and “black death”.
Resources for further information for Monarch Butterflies
If you are not sure which milkweeds will grow in your area you can look at this guide created by the Texas Parks and Wildlife that shows where certain milkweeds are found. Look toward the bottom of the page for – Identify Milkweed.
The U.S. Forest Service has a great guide that shows the actual migration paths that monarchs take both to and from Mexico.
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