According to the University of Kansas website, Monarchwatch.org, the massive annual butterfly migration is all but over for Texas. According to their update map, the butterflies are almost through the west Texas area and down into south Texas and northern Mexico.
The peak migration thorough Texas begins in September and usually ends by November. October 25th until November 7th marks the tail-end of the migration through this area.
The thousands upon thousands of Monarch butterflies that pass through Texas every year begin their journey northward from Mexico in the spring. This year was one of the largest migrations in recent years. The butterflies feast on milkweed as they pass through Texas onto the northern areas of the United States and southern Canada to lay their eggs. By the end of spring they’re usually up north of Oklahoma as well as out in Arizona and California. They spend their summers in the Corn Belt before heading back south in the fall.
The total population of Monarch butterflies is estimated to be around 300 million butterflies. The encroachment of humans threatens the migration more and more every year as rural land where their source of food, milkweed, is developed for homes and businesses.
Each Monarch will lay from 300-500 eggs, and like all creatures in the natural world, have natural predators and a changing climate to deal with. Of those 300 million butterflies, Monarchlab.org hypothesizes that 50% are female. With an estimated 150 million female Monarchs laying 300-500 eggs it wouldn’t be unusual to believe that the population was firmly established. Even at 300 eggs each, that would mean that annually, around 45 billion butterflies are born. That doesn’t take into account the hatch rate of the Monarch and it doesn’t show the number of generations required just to make the annual migration. Eggs laid on milkweed plants in March and April hatch into baby caterpillars after 4 days. The caterpillars feed on the milkweed plants for two weeks and then find a handy spot to begin the process of their metamorphosis. The caterpillar then enters they chrysalis phase for 10 days. A second generation will be born in May and June and then a third generation in July and August. Each butterfly dies 2-6 weeks after it’s born.
The journey of the Monarch butterfly is lengthy and requires generation upon generation just for one annual migration. Much like salmon that return to their home rivers to spawn and then die after mating, the butterfly has a similar lifecycle. Their goal, like the salmons, is to mate and they do so in the same area year after year and decade after decade. The cycle is never-ending with one generation dying as the next generation carries on the journey.
Monarchs can still be found in the area, some recently spotted at the San Angelo State Park’s North Shore unit along the North Concho River. Their orange and black colors perform a startling contract to the green of the trees they will set upon during the evening and nights. Hundreds at a time will fine a perfectly suitable tree branch for resting upon, typically one that is bare of foliage. The Monarchs themselves, when grouped in hundreds on this bare branches themselves look like leaves until you walk up to them and the all take to the wind and flutter away.