by Jennifer Trandell, PWL Member
The incredible 3000-mile North American journey of the Monarch butterfly (Danaus plexippus) happens twice a year. In spring, as the weather warms, the roosting butterflies of Mexico spread their wings to fly north to Canada. As soon as springtime milkweed plants are available for depositing eggs, mating begins. It will take several generations to complete the northern trek. The Monarchs that emerge from the eggs along the northern route will continue to breed and lay eggs, completing the cycle north. However, in the autumn migration group, the southerly journey becomes the responsibility of a single butterfly.
The spring migration is the remarkable journey of Monarch butterflies returning north from their wintering grounds in Mexico to breed and lay eggs in North America. This migration typically occurs between March and May and is essential for the survival of the species. Spring adult butterflies live for only 2 to 5 weeks. Mating and laying eggs is of utmost importance. The butterflies travel gradually northward, with the first wave of Monarchs reaching Texas and the southern United States by early spring. These butterflies are typically not the same individuals that left the northern areas the previous fall, but rather their offspring.
The Monarch butterfly is the official state insect of Texas. The Rio Grande Valley and other southern regions of Texas provide vital habitat, including nectar sources and the host plant for Monarch larvae, milkweed. The first generation of butterflies rely on these areas to fuel their journey and reproduce. Texas is a crucial area for the Monarchs as they pass through on their way north to the summer breeding grounds. The likely springtime migratory route of a Monarch butterfly is through central Texas into the Great Plains of the United States northward or to the East along the Gulf Coast and Eastern Seaboard to Southern Canada. However, inclement weather or areas affected by drought can alter their migratory path. The Piney Woods of East Texas is not typically a major migratory pathway of the Monarch butterfly’s northern route but due to climate change and other environmental factors more Monarchs are appearing amongst the trees.
By migrating north the mighty Monarch can expand into over 1 billion acres of breeding habitat from the 15 acres of habitat they occupy during the winter in Mexico. However, habitat loss due to agricultural and urban development has resulted in the disappearance of millions of acres of grasslands throughout the United States. Extreme weather events including drought and wildfires have also diminished the availability of nectar and host plants during spring and fall migration. Pesticides, herbicides, and predation by invasive species, such as the fire ant (Solenopsis invicta), are also depleting the number of pollinators throughout the Monarch’s native range. Scientists studying the Monarch have found the summer population of breeding butterflies to have substantial numbers. The worrisome decline in the winter population returning to Mexico indicates the problem lies within the migration pathway.
5 Easy Ways to Help the Monarchs Migrate
Helping monarch butterflies migrate involves creating habitat, reducing threats, and supporting conservation efforts. Here’s what you can do:
- Plant native milkweed to support breeding activity along the migration path.
- Grow nectar-rich flowers to provide nutrients and energy during migration.
- Reduce pesticide and herbicide use.
- Provide shelter by planting native shrubs and practicing no-mowing in late winter and early spring.
- Provide water in shallow trays, bowls or ponds.
