We have bees and other pollinators to thank for pollinating over 70 percent of all flowering plants which results in the production of seeds and fruits. Beyond agriculture, pollinators are an important part of the native ecosystem as they contribute to the food production for many seed and fruit eating birds and mammals. Unfortunately we are experiencing a decline in the number of pollinators, especially bees, that play this important part in our food production. Two of the principle pollinating bees are the honey bee and the bumble bee.
Bees can be divided in two groups based on their ‘lifestyle’ — some are social and some are solitary. Honeybees and bumblebees are social bees, meaning that they share a nest and the work supporting their colony. Honeybees are non-native bees that are used for pollination and honey production. They have perennial hives that survive the winters on stored honey. The recent decline of honeybees, with what has come to be known as colony collapse disorder, has been well documented. More recently we have begun to see a decline in the number of bumblebees.
Bumblebees are fat, hairy bees that nest in the ground and are primarily used for pollination; sometimes to pollinate greenhouse crops, but mostly in the wild. Native to North America, there are 48 common species of bumblebees, whose habitat ranges from southern Canada to northern Louisiana and east. 23 species are common in Minnesota and over the last 20 years we have witnessed a serious decline in both numbers and range in five species, and a less serious decline in three species. One species bombus affins, the rusty patch bumblebee, has seen a decline of 87 percent, resulting in it being added to the list of endangered species under the Endangered Species Act of 1973. There are number of possible causes for this decline — including disease, climate change, loss of habitat, lack of food and increased use of pesticides.
Considering that bees pollinate of over 100 crops in the United States, contributing over $18M in crop yields, this decline in the bee population is quite alarming. While the decline has occurred across Minnesota, bumblebees are still somewhat abundant in the Twin Cities and there are some things we can do in our lawn and gardens to help stop the decline and support bumblebees. We can add to their nesting habitat, increase their food supply and reduce our use of pesticides.
We can create a welcoming habitat. Most bees, 60-70 percent, dig burrows in the ground for their nests. They prefer dry, sandy soil with little or no vegetation. Providing a small bare spot in our yard or gardens for them to nest would add to their ability to increase their numbers. Some bees make their nests in cavities, such as hollow stems or holes in wood. You can purchase bee houses at some local nurseries or can make your own bee houses by creating hollow stick bundles or leaving out a block of wood with many holes drilled in it.
Bees get all of their nutrients from flowers; we can add to their food supply by planting flowering plants, trees and shrubs. Bees get their protein for strength and growth from pollen, and their carbohydrates for energy from the flower nectar. Different species prefer different flowers. Ideally we should plant a variety of plants that bloom and provide nutrients consistently across the seasons, April through October. Native plants are best as they are well adapted to our environment. Avoid plants that have been bred for show, they may not have adequate pollen or nectar for the bees.
Some plants that would add to the bee food supply in spring are rhododendrons and azaleas, beardstongue, gooseberry and willows; in the summer bee balm, anise hyssop, purple prairie clover and Joe Pye weed; and in the late summer and fall, asters and goldenrod.
You also may have heard of a “bee lawn.” This is a lawn in which some broadleaf weeds are allowed to grow. Dandelions are sometimes the only food source for bees in early spring when they are a plentiful source of nectar/carbohydrates. Dutch white clover has smaller quantities of nectar but there is high protein content in the pollen. Even creeping charlie flowers have a high sugar content in the nectar. If you can, allow a few dandelions and some Dutch clover in your lawn in the early spring until other plants begin to flower and there are other sources of nutrients for the bees.
Keep your flowers clean by reducing your use of pesticides, including insecticides, herbicides and fungicides. Insecticides are intended to kill insects and many are harmful to bees. Herbicides which kill plant material can eliminate some of the weedy flowers that the bees feed on. Even fungicides can be harmful to bees by destroying some of the beneficial microorganisms in their guts.
The decline in the bee population is indeed distressing, but we can be part of the solution to the problem if we choose to do so.
Correction
In the March Camden News the article entitled “The best plants for tough urban sites” had the wrong byline. The article was written by Amy Chapman. We apologize to her and for any confusion to our readers.