Monarch butterflies reach highest levels of past 25 years, experts say

If you've noticed more Monarch butterflies than normal migrating through your suburban backyards, you're not alone.

The iconic insects known for their bold orange and black wings are being observed in Illinois at some of the highest levels of the past 25 years as they migrate south for the winter. Preliminary data collected by the Illinois Butterfly Monitoring Network shows Monarch butterfly population is at the fourth highest level since 1993.

"Monarchs have had a very good year," said Doug Taron, the director of the butterfly network and chief curator of the Chicago Academy of Sciences.

Why? The answer is difficult to pinpoint, Taron says. Various factors affect the species' health, including weather, parasites and disease.

Unfortunately, the data from a single year does not indicate a long-term upswing for the Monarch butterfly, which suffered an 88 percent decline in North America from 1999 through 2012, according to the Illinois Department of Natural Resources. In Illinois, the overall population trend has neither increased nor decreased during the past several years, Taron said.

Migrating monarchs will peak in the Chicago area sometime during the next couple of weeks, experts say. After that, their numbers will decrease as more and more head toward their final destination in Mexico.

"It's such a beautiful and charismatic species," Taron said. "Its biology is amazing and fascinating. We're continuing to learn so much about it."

Here are a few ways to make your backyard and garden more attractive to Monarch butterflies:

• Plant native milkweed plants, which Monarch larvae eat. Five varieties are easy to find: common, swamp, butterfly, horsetail and poke.

• Add plants that provide nectar such, black-eyed Susans, blazing-stars, purple coneflower, goldenrod asters, ironweeds and wild bergamot.

• Avoid using pesticides or cutting the lawn too often.