Thanks to more Monarchs reaching the overwintering sites in the fall and a very mild winter in their breeding grounds in Mexico, the number of Monarch butterflies appears to be rising and could top more than 100 million this year, says a Texas A&M University researcher.
Craig Wilson, a senior research associate in the Center for Mathematics and Education and longtime butterfly enthusiast, says early figures for Monarch numbers in 2016 are promising and could reach 100 million this year – almost double from numbers a year ago — and that would be good news considering that only a few years ago, their numbers were in the 33 million range.
“It seems conditions have been successful for Monarchs overwintering – not too wet or cold, which can be a lethal combination for them,” he says. “Massive mortality from severe winter storms has not occurred.
“The numbers I have seen from various sites and experts all point to about 100 million this year. It means their numbers are gradually increasing, but you have to remember that their numbers were in the 1 billion range only 20 years ago.
“So looking at it another way, the projected numbers are still only one-tenth what they used to be in 1996.”
Wilson says that Monarchs breed in Mexico and then have three more generations as they travel north to Canada.
“Texas is a critical place for them – they have to pass through the state on their way north and lay eggs,” he points out.
It is critical that Monarchs have access to milkweed, the only type of plant that Monarch caterpillars will digest as the multiple generational migration heads north.
But the prevalence of herbicide-resistant crops, very dry conditions over much of Texas and numerous wildfires have hampered their 2,000-mile journey to Canada in recent years. A study from the U.S. Fish and Wildlife Service says that about 1 billion Monarchs have vanished since 1990.
Wilson says more milkweed is needed for the Monarch’s long-term survival.
“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,” he notes. “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.
“It is encouraging that when the migration does take place in late March and early April through Texas, cities like College Station and Bryan, whose mayors have committed to the Mayors’ Monarch pledge to plant Monarch friendly habitats within city limits with milkweeds to feed the nascent caterpillars, will be supporting efforts to help Monarchs.”