Dearth of monarchs migrating through Dallas area concerns butterfly enthusiasts
File 2006/McClatchy-Tribune
Monarch butterflies’ declining numbers stem from habitat destruction blamed on factors such as last year’s Texas drought and wildfires and increased agricultural use of herbicides.
By ERIC AASEN Staff Writer eaasen@dallasnews.com
Published: 01 April 2012 10:27 PM
Springtime is prime time for watching the monarch butterflies that flutter from Mexico through Texas as they make their annual northbound journey.
But the monarchs are dwindling. The Mexican monarch population was down 30 percent this past winter, the latest in a years-long decline.
Blame this year’s decrease on several factors, including last year’s drought and fires throughout Texas, which gave monarchs less nectar as they were heading back to Mexico for the winter.
Experts also point to herbicides that are killing milkweed, on which female butterflies lay their eggs.
There’s no immediate danger that the monarchs will become extinct, but observers in Texas worry about the butterfly’s future.
“The loss of monarch butterflies would be the reduction in the quality of life and the beauty of the world around us,” said Mike Merchant, professor and entomologist with the Texas AgriLife Extension Service in Dallas.
Each spring, hundreds of millions of monarchs make their way north through the United States to the Canadian border. In the fall, they head back to Mexico, where they spend the winter and mate before traveling north again.
The World Wildlife Fund reported that the number of monarchs spending the winter in Mexico dropped by nearly one-third in the last year.
There’s been a decline in the Mexico monarch population since 2003, reports Monarch Watch, a program based at the University of Kansas. The program says the decline is related to increased herbicide use since the introduction of herbicide-tolerant row crops in the ’90s.
Early arrivals
The monarchs’ decline represents changes that humans are making to the environment, Merchant said.
“If something happens along the migration route at one end or another, it can affect the whole population,” he said. “All it takes is one collapse in one of those links in the chain to cause the demise of a species or subspecies of butterfly.”
Despite the sagging numbers, scores of monarchs have been sighted recently across Dallas-Fort Worth.
At Fair Park, several have been spotted at Texas Discovery Gardens each week since early March, said John Watts, an entomologist.
But thanks to a warmer winter, monarchs have been flying farther north earlier than usual. Those early arrivals may run into problems: The milkweed they depend on might not be ready. Without milkweed, eggs won’t survive, and the emerging caterpillars won’t have a food source.
At Fair Park, milkweed grown inside the Discovery Gardens’ greenhouse has been moved outside to help the monarchs, Watts said.
“There’s a good possibility this might be another bad year for them if they can’t find plants to lay their eggs on,” Watts said. “If they get too far north and there are no milkweed plants, they’ve wasted their energy.”
Craig Wilson, a butterfly enthusiast and Texas A&M University researcher, wants to encourage monarch growth by seeing milkweed planted along roads and highways, similar to the wildflowers that are sown across Texas.
Watts says that you can even plant milkweed in your backyard.
“You don’t need a lot of garden space,” Watts said. “Any little bit helps.”
‘Just magical’
Through the winter, monarchs hang out in an area northwest of Mexico City. They cluster together for warmth — and they mate.
In February, they begin their journey north.
The butterflies lay eggs and die, while their offspring continue to migrate northward, as does the next generation. Those that reach the Canadian border live the longest — up to nine months.
“Those are the lucky ones,” Wilson said.
During that time, they “feed like crazy” to build up fat reserves for the long journey back to Mexico, where they’ll spend the winter, Wilson said.
“It’s one of the world’s great migrations,” he said. “It’s just magical. The world is a little less rich if we lose something like that.”
AT A GLANCE: Migratory monarchs
Frequent fliers: Monarchs typically migrate about 30 miles per day. Some have flown hundreds of miles in just a few days, thanks to favorable winds.
A short life: During the summer, monarchs typically live two to five weeks. But those that fly from Canada to Mexico can live up to nine months.
Who knew?: Monarchs are “notably promiscuous,” Monarch Watch says. Females produce offspring that have been “fathered by a series of males.”
A game of tag: In the fall, during the State Fair of Texas, the Texas Discovery Gardens tags monarchs that are flying through the area as part of a program that helps researchers track their southern migration.
Websites: Monarch Watch — monarchwatch.org; Texas Monarch Watch — texasento.net/dplex.htm; Journey North — learner.org/jnorth/monarch
SOURCES: Monarch Watch; Dallas Morning News research
