As many as 50 people could attend the monarch butterfly tagging event in Moraine State Park in Portersville, Pennsylvania. Yet the group will be lucky if it tags a single one, park officials say.
"They are just not around the way they used to be. I have probably only seen five this year, and I look for them all the time. Years ago, there were so many more," said Stephanie Taylor, an educator at the park.
The population of monarch butterflies has declined 90 percent in the past two decades, according to the Center for Biological Diversity, an environmental group that blames the decline on herbicides and the planting of genetically engineered crops in the Midwest, where monarchs once thrived. The butterfly is a pollinator, though not as important as honeybees, whose numbers are falling sharply as well.
Last month, the biodiversity center, the Center for Food Safety, the Xerces Society — another environmental group — and monarch scientist Lincoln Brower petitioned the federal Fish and Wildlife Service to declare monarch butterflies an endangered species.
The groups say the butterfly's population has fallen from a high of 1 billion in the mid-1990s to about 35 million last year.
"Monarchs are in a deadly free fall, and the threats they face are now so large in scale that Endangered Species Act protection is needed sooner rather than later, while there is still time to reverse the severe decline in the heart of their range," said Brower, a professor at Sweet Briar College in Virginia who has studied the monarch for 60 years.
It's estimated that the orange and black butterflies may have lost more than 165 million acres of habitat, an area the size of Texas, including nearly a third of their summer breeding grounds.
In the space of a month, monarchs lay eggs on milkweed leaves that hatch into caterpillars, morph into chrysalises and transform into butterflies.
The butterfly's dramatic decline is being driven by widespread planting of genetically engineered crops in the Midwest, where most monarchs are born, according to the petition filed with the federal government.
Among the most easily recognizable of butterflies in North America, a single monarch can travel thousands of miles from Canada to the same spot in Central Mexico every winter.
"It's such an unusual and magnificent migration," said June Bernard of Hampton, an educator at the Pittsburgh Zoo who raises and tags monarchs.
"I have not seen as many this year. I have friends and have talked to people who said they have not seen them either," said Bernard, whose first recovered tagged Monarch flew 1,872 miles to Mexico in 2003.
Bernard has tagged 125 monarchs this year.
Not everyone is a proponent of classifying monarchs as endangered.
"That could take 10 years. We want to concentrate on restoration, which can be done now," said Chip Taylor, a professor of ecology and evolutionary biology at the University of Kansas and the founder of Monarch Watch.
Genetically modified crops and the corn ethanol mandate have all but eliminated milkweed, the monarch caterpillar's only food, in many farming areas, Taylor said.
Most genetically engineered crops are resistant to Monsanto's Roundup herbicide, which the petition says kills milkweed. Requiring corn ethanol in gasoline has resulted in fewer acres of uncultivated land for milkweed.
A Monsanto spokeswoman said the issue is that farmers have to limit weeds, such as milkweed, to grow crops. The company is working with experts to establish more habitats for monarchs outside farmland, spokeswoman Charla Lord said in an email.
Without milkweeds, monarchs are not able to produce successive generations that result in the yearly fall migration. Without nectar from flowers, the monarchs are unable to make their long journey to Mexico.
"It's symbolic of a bigger problem. Many pollinators are in decline," Taylor said.