Starting in March, millions of monarch butterflies will begin making their spring migration through Texas from their winter home in Mexico to all points north, as far as Canada.
“Monarch butterflies begin to leave their Mexican wintering sites in mid-March and have usually all departed by the end of March. At this point, many of them have already mated, but both sexes leave the sites and migrate north and mating continues throughout the journey north,” says MonarchNet.
The monarch butterfly is the official insect of the state of Texas and for good reason, as the Lone Star State is a key destination for monarch butterfly migration in the spring and fall.
“Texas is an important state in monarch migration because it is situated between the principal breeding grounds in the north and the overwintering areas in Mexico,” explains Texas Parks and Wildlife (TPWD). “Monarchs funnel through Texas both in the fall and the spring.
Spring Migration vs. Fall Migration: Monarch Butterflies
The spring migration for monarch butterflies is not simply a mirror image of the fall migration. While a single monarch will make the arduous migration in the fall, the spring migration will take generations for monarchs to reach their summer home.
- Fall Migration: During the fall, according to TPWD, monarchs use two principal flyways. One traverses Texas on a 300-mile-wide path stretching from Wichita Falls to Eagle Pass. Monarchs enter the Texas portion of this flyway during the last days of September. By early November, most have passed through into Mexico. The second flyway is situated along the Texas coast and lasts roughly from the third week of October to the middle of November.
- Spring Migration: Early each March, overwintering monarchs, according to TPWD, begin arriving from their overwintering grounds in Mexico. Seeking emerging milkweeds, they move through Texas laying eggs before dying. Their offspring continue heading north, leaving most of Texas behind. They’re the first of several new generations of monarchs that re-populate the eastern half of the United States and southern Canada.
“The monarchs that overwinter in Mexico fly north to repopulate the southern half of the US, and their offspring complete the journey to the northern US and southern Canada,” says MonarchNet.
While a single monarch will fly up to 3,000 miles in the fall to make it to the Mexico winter grounds, it will take as many as four generations to complete the return trip in the spring as the spring monarch butterflies have a lifespan of approximately 3 to 5 weeks. Alternatively, the fall monarch butterflies can live as long as nine months.
Unlike in the fall, when large roosts of monarchs migrate together, the spring migration is much more spread out and sporadic.
According to Texan and monarch biologist Dr. Bill Calver, “It’s not dramatic … you never see too many monarchs at once. You may see one or two an hour, and that would be a good spring migration. Sometimes along the coast, you may see ten or twenty at once, but that would be during a very strong migration. The reason you see so few in the spring is that there are far fewer monarchs alive in the spring than in the fall. There has been mortality at the overwintering sites in Mexico and mortality along the migration. Your chances of seeing high numbers of monarchs at once are not good. They’re just too dispersed.”
Spring Migration and Importance of Texas Milkweed
Texas has about 30 native milkweed varieties, which play an essential role in migrating monarch butterflies in the spring, providing food for their caterpillars and a place to lay eggs.
“As warm temperatures and lengthening days arrive, the migratory generation of monarchs finishes the development they halted prior to their migration. They become reproductive, breed, and lay the eggs of the new generation. This starts the northern journey back to North America. Unlike the generation before them, who made a one-generation journey south, successive generations make the journey north,” says the U.S. Department of Agriculture.
The World Wildlife Fund (WWF) says that milkweed is the only plant on which monarchs will lay their eggs and the only source of food for baby caterpillars.
“Planting the right species of milkweed in a given area can help these amazing butterflies and other pollinators thrive,” says the WWF.
WWF says to follow these 3 steps to add milkweed in your area for monarch butterflies:
- Know Your Milkweed: In Texas, some milkweed species to consider include Green Milkweed, Antelope Horns Milkweed, and Zizotes Milkweed. The Native Plant Society of Texas says the Antelope Horns and Green milkweed species are very common, growing in pastures and along roadsides throughout the central flyway of Texas, the path that most monarchs take on their migration through Texas.
- Find Your Milkweed: Locate a nursery or other plant retailer in your area with the right kinds of milkweed or buy milkweed directly from a supplier such as Monarch Watch. To help as many monarchs as possible, plant a variety of milkweed as well as other plants that provide adult monarchs with nectar. For example, choose plants that bloom at different times of the year to help monarchs as they fly south at the end of summer and north in the spring as they return to their breeding grounds in the US and Canada.
- Plant Your Milkweed: The plants should come with instructions. Make sure your milkweed is planted in as much sunlight as possible and shield it from wind. Consider containers in difficult areas or if space is limited.
Monarch Butterflies’ Effect on the Ecosystem and Other Facts
Monarch butterflies play an important role in our ecosystem.
“Monarch butterflies are not just breathtaking to watch—they play a crucial role as pollinators, supporting ecosystems across North America. During their migration, they carry pollen between flowers, aiding plant reproduction and benefiting the wildlife that depends on those plants for food,” says MonarchNet.
Here are some other monarch butterfly facts:
- Long Flights at Elevation: We think of butterflies floating around ground level but on their migration, they can fly as high as 800 to 1,200 feet, while traveling up to 3,000 miles.
- First Time, Every Time: Since the monarchs that migrate north in the spring will breed and pass away before their descendants are ready to migrate south again, none of the monarchs on the fall migration path have ever been to their destination before. The Xerces Society for Invertebrate Conservation says scientists believe they use the sun’s position and Earth’s magnetic field to navigate directionally, but the rest is still a mystery!
- Know Your Monarch: WWF says that adult monarch butterflies possess two pairs of brilliant orange-red wings, featuring black veins and white spots along the edges. Males, who possess distinguishing black dots along the veins of their wings, are slightly bigger than females.
- Best Viewing Spots in Texas: The I-35 corridor is the best viewing spot for monarchs as they travel along its path, hence the nickname: The Monarch Highway. Another viewing spot is the National Butterfly Center in Mission.
Just remember, if you miss the monarch butterflies on their trek through Texas this spring, you have a great chance to catch them again in the fall on their return migration to Mexico.
