Gardeners across the Midwest are reporting fewer numbers of the iconic monarch butterfly, which has struggled against drought, pesticides and vanishing food sources, experts say.
Every summer, like seasonal clockwork, hundreds of monarch butterflies descend on the oh-so-alluring plants in Diane Schutz's garden in Catlin.
They cover her butterfly bush, their orange and black wings a stunning contrast to the dark fuchsia blossoms.
"They're just a thing of beauty," said Schutz, a lifelong gardener. "You could always depend on them to be there, bringing their beauty to your doorstep. It was just like a rite of summer. Now I'm not seeing any."
Though her butterfly bush has abundant blooms, the monarchs are "totally absent," she said Friday.
Gardeners across the Midwest are reporting fewer numbers of the iconic butterfly, which has struggled against drought, pesticides and vanishing food sources, experts say.
Monarch numbers have been declining for years, but several factors affected this year's crop, scientists say. Entomologist Mike Jeffords of the Illinois Natural History Survey in Champaign cited two likely reasons, both related to the drought of 2012.
Milkweed, which the monarch caterpillar relies on for survival, didn't fare so well during the drought in the southern United States last year, with plants even aborting their flowers, Jeffords said. And the drought meant there were fewer nectar plants for adult monarchs to feed on for a 1,000-mile stretch of terrain on their way back to Mexico, he said.
Scientists who survey the monarch's wintering grounds in central Mexico reported the population this year was 80 percent below the average of 350 million, according to Journey North, which tracks wildlife migration.
A cool, wet spring may also have delayed the appearance of monarch and other butterflies in the Midwest this summer, along with other butterflies, scientists say.
"A lot of our caterpillars have gotten fungus diseases," said entomologist Phil Nixon of UI Extension. While other butterfly species are starting to appear, "I haven't seen many monarchs yet. I imagine they will be making themselves known over the next couple of weeks."
"It really seems like the monarch sightings are about a month behind what they should be," said Brian Hayes, co-director of the Monarch Teachers Network, part of a nonprofit based in New Jersey called the Education Information Resource Center.
To understand the extent of the problem, you have to understand the life cycle of the monarch, said Hayes, whose mission is to train educators how to use monarchs to teach any subject and help protect the species.
Monarchs spend the winter in a dozen colonies in the mountains of central Mexico, then head north in early spring and begin laying eggs on milkweed plants in Texas, Louisiana and other southern states. The caterpillars hatch, feed on the milkweed plants, then turn into a pupa or chrysalis, where they undergo a metamorphosis into the orange-and-black butterfly we know and love.
The adult monarchs live three or four weeks, then lay eggs, and the cycle repeats for several generations as the butterflies migrate north throughout the summer up to Canada.
But the last generation of the summer goes into a sort of reproductive hibernation; the hormones don't kick in. Rather than procreate, they fly up to 3,000 miles back to Mexico, where they live for eight months before heading back to Texas. Hormones now raging, they mate, lay their eggs and die, and the process begins anew.
The equivalent for humans would be that every sixth generation would live about 1,000 years, Hayes said. "It's amazing," he said.
Scientists have tracked monarchs for two decades, measuring the size of their winter colonies through aerial surveys. The numbers have been dropping for years, but this past winter scientists found a 58 percent decline in the monarch population over the previous winter, Hayes said.
The monarchs build up their numbers every summer in North America, but they started with such low numbers this spring that "people aren't seeing them," Hayes said.
Scientists won't know the official toll until next winter's aerial count, but "we'll be able to get a better judgment in September."
Scientists blame the overall decline of the monarch on the loss of milkweed and butterfly habitat.
While adult monarchs can eat nectar from many flowers, "milkweed is the only plant the monarchs eat as a caterpillar. If they don't find milkweed, their young won't survive," Hayes said.
Milkweed used to be extremely common throughout the farming belt, and that's believed to be where the majority of monarchs breed, Hayes said. Those who track the butterflies for Monarch Watch, a group based at the University of Kansas, report significant declines in milkweed along roadsides and farm fields.
Though evidence is anecdotal, Hayes said, there's a link to genetically modified crops. They are naturally resistant to pesticides and herbicides, so when crop dusters spray they kill everything but those crops, and "they're killing the milkweed, too," he said. "If there's no milkweed, there's no monarchs."
Butterflies are also losing habitat in every open field developed into a shopping mall, subdivision or parking lot, he said. Lawns are now the second largest drop in the United States, he said, and manicured suburban lawns are "a biological wasteland for insects," he said. "Very little can live in there."
Monarchs face other pressures, including illegal logging in their protected wintering grounds in Mexico, Nixon said.
The monarch is such a popular, showy species — the state insect for Illinois and other states — that lots of people are studying the problem, Hayes said.
Karen Marrero of Champaign, an amateur naturalist who records local monarch sightings for Journey North , is seeing signs of hope. She'd spotted just one monarch all summer in her garden until Thursday, when one appeared on her butterfly bush. It reappeared Friday and hung around for an hour or more, feeding and resting.
The Windsor, Ontario, native planted several milkweed plants after reading about the monarch's plight earlier this summer in a Canadian newspaper. She's keeping her fingers crossed.
"This is a very pivotal area in their journey across the continent," she said.
Schutz, a lifelong gardener, has grown lots of plants to attract both bees and butterflies, and she's planning to add milkweed to the list.
"Even though it's not a big habitat, in my little corner of the world it's a start," she said.
How to help monarchs:
Plant milkweed. Monarchs like three types:
— Butterfly weed (Asclepius tuberosa), not to be confused with butterfly bush, which has bright orange and yellow blossoms and is commonly available at gardening centers.
— Swamp milkweed (Asclepias incarnata), which has pink flowers and can be found in gardening stores that focus on native plants.
— Common milkweed (Asclepias syriaca), typically found along the side of the raod, which also has pink flowers.
Monarch Watch: http://www.monarchwatch.org/ 
Based at the University of Kansas, this organization works with schools, businesses, parks, zoos and others to set up Monarch Waystations across the country. It offers $16 seed kids to set up a waystation with milkweed and other plants essential to monarch breeding.
Journey North: http://www.learner.org/jnorth/ 
This group gathers information from citizen scientists who report monarch sightings across the country, providing a visual map of monarch migration.