The Monarch butterfly, a species found to be in decline, has increased its population by almost 70% compared to last year, according to research conducted at the Texas A&M University. A revived breeding ground for the Monarch butterfly in Mexico may explain the comeback.
The senior research associate at the Center for Mathematics and Science Education, Craig Wilson, who is also an expert in butterflies, explained that the increase from 33 million last year to an estimated number of 56.5 million this year can be attributed to a Mexican breeding ground that is fostering its comeback after decades of decline.
“The winters the last few years have been rough on them, and there is still a lingering drought in and around their breeding grounds. But this has been a fairly mild winter and their numbers are moving in the right direction,” said Wilson in a press release.
Despite the fact that in 1996-97 the population of Monarch butterflies was about a billion individuals, residing in 15 over-wintering Mexican locations, these numbers decreased to about 33 million in only two sites in 2013-14, the lowest yet reported. However, a successful migration of the species last fall is thought to have originated the comeback of Monarchs, with more than 50 million butterflies in nine sites.
“There are still plenty of reasons to be concerned, mainly because the number of milkweed plants — the one plant that is vital to their existence — has been decreasing in the past decade. There are new programs to establish milkweed planting, and the public is urged very much to do so. The Monarch’s survival depends on it,” he continued.
The researcher believes that despite the good news, issues remain over the dwindling population of Monarch butterflies, as there were hundreds of billions of them 20 years ago, and after breeding in Mexico for three generations they are now thought to be heading towards Canada. In this case, they would have to pass through Texas and lay eggs there, which is “a critical place for them,” he said.
“So it’s critical for them that they get milkweed here. It is the only type of plant that Monarch caterpillars will digest as the multiple generational migration heads north,” Wilson explained. The researcher is concerned that the predominance of herbicide resistant crops, as well as dry conditions and wildfires, may make the 2,000-mile journey towards Canada difficult.
“It takes four generations of the insects to make it all of the way up to Canada, and because of lack of milkweed along the way, a lot of them just don’t make it. But if people want to help, they should purchase and plant milkweeds, preferably milkweeds native to their state,” the researcher added, as he is currently gathering several milkweed plants to the ones already existing at the Cynthia Woods Mitchell Garden, in the campus of Texas A&M.