The small town of Blanchard, Oklahoma, threw a big party this fall, but the guests of honor did not show up. Residents suspect foul play somewhere on the guests' international trek to the festivities.

To make sure the same thing does not happen next year, Blanchard residents called on farmers in Oklahoma to plant more milkweed, cut down on pesticides and clear a favorable path for the monarch butterfly - the missing celebrity at its annual Monarch in the Park festival during what was supposed to be the insects' arrival on their arduous annual migration.

"We released three monarchs. ... Woo hoo," said organizer Zereta Sucharski at the time of the Sept. 30 festival.

Millions of the orange-and-black butterflies make the 3,000-mile (4,800 km) journey each year from Canada to spend the winter in central Mexico, but the size of that migration can vary wildly.

While an estimated 1 billion monarchs migrated in 1996, only about 35 million made the trip last year, according to Marcus Kronforst, a professor of ecology and evolution at the University of Chicago who has studied monarchs.

Chip Taylor, director of Monarch Watch at the University of Kansas, said the butterflies have suffered from the expansion of farmland, sprawling housing developments and the clear-cutting of natural landscapes along their migration path.

"Destruction of habitat is the main problem with declining monarch population," he said.

Last year's population of migrating monarchs was an all-time low, Taylor said. The accumulated loss over about five years of breeding grounds roughly equal in size to the state of Texas further hurt the population numbers.

The monarchs' long-distance travel to their wintering roosts is a marvel, and a bit of a mystery.

Millions of butterflies fly en masse, often alighting on the same trees their grandparents used. But they make the round-trip only once; their offspring head north the following fall.

After milkweed

In Blanchard, a town nearly 8,000 people 25 miles south of Oklahoma City, buttefly advocates are working with the state to make the monarchs' trek through Oklahoma a little safer by ensuring that there are plenty of places for the insects to feast, rest and multiply along the way.

If that works, residents say, they would like to seek changes on the entire route.

Sucharski said festival backers are trying to persuade farmers to leave milkweed along fence lines and pressing the highway department to leave the plants alone.

"We give away milkweed seeds and flowering seed balls to whoever wants them," she said.

Monarchs lay eggs only on milkweed plants, which grow wild throughout the United States. But milkweed can cause stomach problems for cattle that eat it, so ranchers and farmers destroy it.

The insects' plight has become an international issue. In February, the United States, Mexico and Canada agreed to set up a joint task force to protect the winged insects.

"It is a landmark species in North America," Mexican President Enrique Peña Nieto said at the meeting.

In Blanchard, the message has come through loud and clear.

"It may not seem like much, but just planting milkweed and cutting back on pesticides helps," said Sucharski.

"If we don't, then no more monarchs."