Monarch Migration in Texas Timeline

Monarch Migration in Texas 19

Early March Monarchs return to Texas The first butterflies arrive from Mexico Monarchs that spent the winter in the mountains of central Mexico cross the Rio Grande into Texas. Texas is the first place where they breed after the winter.
Mid-March Eggs laid on Texas milkweed Antelope-horn and green milkweed Females lay their eggs one at a time on milkweed, the only plant monarch caterpillars can eat. In Texas they rely mostly on native species such as antelope-horn milkweed.
Late March The first spring generation hatches Caterpillars on milkweed Eggs hatch after about four days. The caterpillars feed on milkweed for around two weeks, taking in toxins that make them, and the butterflies they become, distasteful to birds.
Late March to April The old travellers die End of an eight-month life Having flown to Mexico in the fall, survived the winter and laid their eggs in Texas, the last of the super generation die. Few live longer than eight or nine months.
Early April Caterpillars form their chrysalis About ten days Each fully grown caterpillar hangs upside down and turns into a green chrysalis with gold spots, from which the adult emerges after about ten days.
Late April The first generation flies north From Texas to the Midwest The new adults, born in Texas, continue the migration north towards the Midwest and the Great Lakes. Like the summer generations, they live only two to six weeks.
May Texas empties for the summer Heat and dry milkweed As the heat builds and milkweed dries out, most monarchs leave Texas for the north, and few are seen in the state until the fall.
June The second generation in the north Midwest and southern Canada Their offspring hatch on milkweed across the Midwest, the northeastern United States and southern Canada, the main breeding grounds of the eastern population.
July to August The third generation Peak breeding season A third summer generation follows. Numbers peak in late summer, when the population is at its largest of the year.
Late August The super generation emerges Born to migrate Butterflies that emerge as the days shorten do not mature sexually. Instead they store fat and live up to eight months, long enough to fly to Mexico and back to Texas.
September The flight south begins Up to 4,800 kilometres The super generation sets off from as far north as Canada on a journey of up to 4,800 kilometres, steering by the sun with an internal clock and, scientists think, the Earth's magnetic field.
Late September Migration enters North Texas The Central Flyway Monarchs from the Midwest funnel into Texas along the Central Flyway, crossing North Texas from late September.
October A second route along the Gulf Coast The Coastal Flyway Monarchs from further east follow the Texas Gulf Coast, where they feed on late flowers before heading inland towards Mexico.
Early to mid October Peak migration in Central Texas Roosting in the trees The migration peaks over the Hill Country and Central Texas, where thousands of monarchs can gather overnight in pecan and oak trees. Fall nectar plants in Texas are the fuel for the last part of the journey.
Late October Monarchs cross the Rio Grande Leaving Texas The last wave passes through South Texas and crosses into Mexico, heading for the mountains of Michoacán and the State of Mexico.
Early November Arrival in Mexico for the Day of the Dead The oyamel fir forests The monarchs reach high-altitude forests of oyamel fir west of Mexico City around the start of November, when Mexicans celebrate the Day of the Dead. Many see them as the returning souls of the dead.
December to February Millions clustered in the firs The Monarch Butterfly Biosphere Reserve Packed together in their millions, the butterflies cover the trunks and branches and stay mostly still through the cool winter. The reserve became a UNESCO World Heritage Site in 2008.
Late February to March Mating and the flight north The return As the days lengthen the monarchs mate and leave the forests, flying north to lay their eggs in Texas and start the cycle again.
March Back in Texas The cycle starts again The same butterflies that left Texas in October return in March, and the first generation of a new year begins on Texas milkweed.