Pollinators Imperiled

by Susannah Wood

The declining population of monarch butterflies, those champions of migration, has been well-documented over recent years, but has only become more dire. Between 1996 and 2020, 88 percent of the eastern population of monarchs has disappeared. In the western group the situation is even worse; only a few thousand remain. Continuing losses of honey bees across the globe have farmers and beekeepers seriously worried. But these declines are only a tiny piece of a much bigger story. Many other pollinator species are also in serious decline. In the United States, 70 species, including bats, wild bees, flies and nearly 40 butterflies are listed as either threatened or endangered, with many others losing significant numbers. 

What is driving these steep declines? Scientists cite several threats: loss of connected habitat due to development and fragmentation of landscapes, application and drift of pesticides and herbicides and diseases that have spread from commercially raised bees and bumble bees. Climate change has caused shifts in plant blooming times so that pollinators may emerge after a particular species has already flowered. According to the U.S. Fish and Wildlife Service, the greatest losses in bumble bee populations have occurred where temperatures have risen the most. Indirect effects also play a role, such as increased wildfires, more and more violent hurricanes, flooding and invasive species. 

Kimberly Stoner, director of etymology at the Connecticut Agricultural Experiment Station (CAES), points out that 87 percent of all plant species need pollinators. Roughly 75 percent of all food crops are pollinated by wild bees and honey bees. Native bees are vital pollinators for both agriculture and ecological diversity. More than 300 species of bee have been identified in Connecticut, including sweat bees, green bees, cellophane bees, bumble bees and miner bees. Squash bees, for example, pollinate cucumbers and pumpkins, while mason bees are important fertilizers of fruit trees. Bumble bees quiver in a way that makes them highly effective at gathering pollen and are used in greenhouses to fertilize tomato plants. Bees make particularly good pollen gatherers because of their hairy bodies, but beetles, wasps, flies, bats, moths and hummingbirds also act as pollinators.

Stoner is a bumble bee specialist. Of the 16 species historically present in Connecticut, two have completely disappeared— the rusty-patched bumble bee and Ashton’s cuckoo bumble bee— and several others, including some that were once common, have decreased significantly.  To learn more about the state of local wild bees, Stoner and her team have conducted surveys in and around Norfolk, including in Great Mountain Forest, because many native species are only found in the Northwest Corner. One piece of good news is that the yellow-banded bumble bee, Bombus terricola, a species only found here, seems to be making a comeback. Tracy Zarillo, who has the wonderful title of Mellitologist at the CAES, does much of the bee work. She explained how some bees are specialists. For example, a long-horned bee, Melissodes denticulatus, prefers ironweed, a common late summer native with striking purple flowers, while the aster miner bee, Andrena asteris, prefers to feed its young with the pollen of aster species, but also will feed on goldenrod. 

So, what can be done? Efforts are underway across the country to support native pollinators and honey bees. Something of a crowdsourcing program called “Pollinator Pathways” is encouraging citizens to create connected swaths of native plantings through their communities. Supporting pollinators does not require ripping out existing gardens. It means evaluating gardens with an eye to supplying pollinators with a steady variety of appropriate plants throughout the growing season. Bumble bees, for example, rely on flowering trees and shrubs early in the season, such as blueberry, service berry, chokecherry and native and even non-native rhododendron. In summer, lawns with red and white clover, also non-native, are very good for bumble bees; in fall, goldenrods and asters provide food sources for many species. One possible combination to try: wild geranium and native blueberry for spring; swamp milkweed and New Jersey tea for mid-summer; and New England aster and a variety of goldenrods for late summer and fall. Blanket flower and stonecrop, while not native to this area, are also good choices. One benefit to native plants is that they need little watering once established.

Many annuals have been genetically altered and no longer provide much nectar or pollen. Some, however, are still good sources of both. These include sweet alyssum, ageratum, borage, cosmos, spiderflower, sunflower (not the pollenless varieties), Mexican sunflower, pineapple sage and some types of zinnias and verbena. Perennials are still best, offering more nectar and pollen. Herbs such as basil, chives, lavender, oregano and rosemary, if allowed to flower, will also feed both honey bees and wild bees.

As most know, milkweed is essential for monarchs. With more invasive plants taking over roadsides, planting milkweed has become even more important. Swamp milkweed, showy milkweed and butterfly milkweed are the best choices and should be grouped with at least six plants together.

Minimize or completely eliminate pesticides. Be aware that many nursery-sold plants are treated with pesticides prior to sale, so speak with nursery staff or seek out growers that don’t use pesticides. Many pests can be kept at bay with insecticidal soaps. If using biological pesticides such as Neem oil or soap solution, apply it early in the morning or late in the day when pollinators are not active. 

Reduce the size of lawns and don’t fertilize with high-nitrogen fertilizers. Overseed with red and white clover in spring.

Leave a bare patch of earth near the garden for ground-dwelling bees to make their home and a brush pile or downed log at the edge of the yard for overwintering.

Ask at the nursery for native plants and encourage them to expand these offerings. 

More information is on the way in August when the Conservation Commission will host a presentation on pollinator gardening through the Norfolk HUB. Additional resources are listed below and on NorNow.org.