How Illinois’ more than 400 bee species are supported by native plants — and how you can help them, too

With plant sales booming and education about insects becoming more commonplace, awareness of both native plants and pollinators has grown significantly over the past decade. But amid all the success, one local environmentalist is asking, “What about the bees and trees?”

Native bees have long been overshadowed by their European counterpart, the honey bee. And while native garden plants such as wild bergamot and common milkweed are vital resources for pollinators, one needs only to look up to find that trees are just as important — especially for the more than 400 native bee species in Illinois.

“Trees especially in the spring are critically important for bees,” said Lonnie Morris, the founder and coordinator of the DuPage Monarch Project. “Many people don’t even know that trees like a sugar maple or red maple have flowers, because they’re teeny tiny and they don’t have big petals. But they do have nectar and pollen for bees.”

Morris’ interest in bees and trees began when she came across research from pollinator conservation specialist Kass Urban-Mead, who has documented the deep, unexplored relationship between bees and forests.

To wild bees, tree canopies are mating sites, micro habitats and places to collect honeydew, sap and resin. But most importantly, Urban-Mead said in a recent webinar, trees provide abundant pollen and nectar resources for bees. Urban-Mead’s research process includes climbing up into trees, collecting bee specimens and even dissecting the insects to confirm the significant presence of tree pollen.

“A tree in many cases, or a shrub, is a great way to diversify not just the season because they usually bloom early, but also just to add a huge burst of resources,” Urban-Mead said in the webinar, adding that a single sugar maple tree can make more than 100 billion grains of pollen.

Trees help bees, and vice versa.

Honey bees often take the spotlight as a well-known agricultural pollinator, but in almost all crops, native bees are the primary pollinator or they significantly supplement the activity of honey bees, according to the U.S. Geological Survey.

This is exceptionally applicable to fruit trees, something Westmont forester Jon Yeater knows all too well.

Alongside caring for roughly 12,000 public trees as the village’s Forestry & Grounds Division, Yeater manages native mason bees in his backyard to promote better pollination of his orchard.

The hobby began when Yeater noticed blue-green metallic bees flocking to the solitary peach tree that had been standing in the yard when he moved in. After a bit of research, Yeater realized they were mason bees, which are known fruit pollinators. The bees’ pollinating efforts combined with Yeater’s pruning techniques, resulted in almost 360 pounds of peaches that first year.

Today, Yeater’s orchard boasts pears, Asian pears, cherries, plums, nectarines, apricots and nine apple varieties.

To support the bees in pollinating the orchard, Yeater puts out trays that feature small, tubular holes running through them, mimicking the cavities in dead wood that mason bees typically nest in.

Once female bees are done pollinating for the season — right around the end of May — they create balls of pollen, nectar and saliva in the trays. Then, they lay their eggs right on them. Once each egg has a pollen ball to nurture it into adulthood, the mothers cap the holes with mud and leaf pieces, leaving the baby bees to hibernate until it’s their turn to emerge the following spring.

The mason bee’s relationship to trees is just one story among the thousands of bees native to the U.S. — many of them smaller in size than a grain of rice. Of the country’s 4,000 native bee species, a whopping 10% have not been named or described.

“We as people kind of assume that we have a lot of knowledge and we know a lot of things, but I think there’s still a lot of things that we don’t understand about the interactions between some of these bees, native or otherwise, and trees,” Yeater said.

Faced with pesticides, disease, habitat loss and climate change, some native bees may never be fully understood. According to the Center for Biological Diversity, one in four native bee species is at risk of extinction.

In a world of scarce resources, native bees also are at odds with honey bees, which are dogged and dominant floral visitors: In a 2017 report in Conservation Letters, researchers found during a three-month period, honey bees in a typical 40-hive apiary collect the equivalent amount of pollen and nectar as 4 million solitary wild bees.

“We all love honey, but we have to make sure that there’s enough forage for them, so that they’re not taking it away from the native bees,” Morris said. “Honey bees can forage for a one-mile radius. That’s huge. Many other bees do not have that capacity to travel that far.”

With about 30% to 50% of all native bees exclusively pollinating from one specific plant they’ve evolved with over millennia, plant diversity also is heavily driving native bee decline.

“If the plant they rely on disappears, the bees go away. If the bees disappear, the plant is unable to reproduce and dies out,” according to the U.S. Geological Survey.

To broadly support native bees, advocates are looking to provide food resources locally. That’s where native plants come in.

Lisa Gerhold-Dirks, chair of Elmhurst Cool Cities, said the group has been promoting pollinators for the better part of the last decade, hosting speakers and tours focused on native gardens.

“There's always room for more education about these things and how important they are and how they work together and how beautiful they can actually be,” she said, adding that she’s seen success in her own green space, especially with the sweet coneflower plant. “I have seen probably six or seven different types of bee species on those flowers that I’ve never seen in our yard before so it really works — and they’re beautiful at the same time.”

With U.S. gardening and lawn care following the same traditional path for hundreds of years, Gerhold-Dirks said she hopes more people will see the value of planting natives.

“Everybody has their own yard. How many other species, not even just bees, are utilizing your yard besides yourself as a homeowner?” Yeater said. “Each individual, depending on what you have on your property, has a significant amount of impact on local pollinators, native bees, birds — everything.”

• Jenny Whidden, jwhidden@dailyherald.com, is a climate change and environment writer working with the Daily Herald through a partnership with Report For America supported by The Nature Conservancy. To help support her work with a tax-deductible donation, see dailyherald.com/rfa.