“To make a prairie it takes a clover and one bee. One clover and a bee, and revery. The revery alone will do, if bees are few.” Emily Dickinson.
Sadly, bee populations are still declining. The way things are heading, bees and prairies may someday both just be things we see in our daydreams. However, like Emily Dickinson’s one bee, each one person who takes steps to help our pollinators is also helping our prairies and the future of our planet. Honeybee decline has made many headlines in the past few years, but bumblebee populations are declining too.
When we think of bees, we usually think of honeybees with their hives full of delicious honey. What many do not know is that honeybees are a relatively recent introduction to Texas. While the first European colonists brought honeybees here in the 1600s, Texas actually hosts hundreds of other bee species that are native. These bee species were here long before the honeybee and play very critical roles in Texas’ diverse ecosystems. These Native Texas Bees developed right alongside our native Texas plants and the two have been working well together for thousands of years.
Bumblebees are mainly social insects, with individual queens establishing colonies during spring. Bumblebee queens nest in or on the ground, taking up residence in clusters of grass or abandoned rodent burrows. After her nest is established, she lays eggs that develop into her first cohort of daughter workers. The queen relies on these workers to forage for nectar and pollen, care for developing larvae and defend the colony against interlopers. At its peak, a bumblebee colony may contain up to 200 workers.
Unlike the colonies of European honeybees, which may persist for years, bumblebee colonies last for less than a single year, from spring into late summer or early fall. New queens, produced at the end of summer, are the only members of the colony to survive into the following year to begin the entire cycle again. The founding queen and all her workers perish as flowers diminish and temperatures drop.
Several once-common species of North American bumblebees are suffering significant range restriction and reduced abundance, according to a recent survey by the Xerces Society. Xerces is an international nonprofit that advocates for invertebrates and their habitats. Surveys like the one on bumblebees are important. Scientists don’t have sufficient data to make a good determination about the status of most bumblebee species, said Robbin Thorp, a professor emeritus in the Department of Entomology and Nematology at the University of California at Davis. “Some species are in very serious decline,” he said. “Some others are doing well and even expanding their ranges.”
While the causes of decline are not fully understood for the species whose populations are decreasing, the likely factors include loss or fragmentation of habitat, pesticide use, climate change, overgrazing, competition with honeybees, low genetic diversity and, perhaps most significant of all, the introduction of nonnative pathogens.
Why should we be concerned about the decline of native bees like bumblebees? As a group, these insects provide essential ecological services that help to maintain natural ecosystems — systems upon which hundreds of other native species depend. Most flowering plants in North America require pollination by insects. Of all the insects that visit flowers, bees are the most important pollinators.
As gardeners we all like to have our neighbors buzzing about how good our garden looks, right? Well, there’s an easy way to do that and it will help an important native pollinator. Plant a bumblebee friendly garden. You’ll do yourself and bumblebees a favor.
Like honeybees, bumblebee colonies produce honey from sugar-rich flower nectar. Honey serves as a food reserve for the colony when nectar is in short supply or when cool, rainy conditions prohibit worker bees from foraging. The amount of honey produced by bumblebees is very small, nowhere near enough for human consumption. Since they store such small reserves, bumblebees require a nearly continuous supply of nectar and pollen from flowers over many months to support and complete colony development.
“Gardening for bumblebees is similar to gardening for other bees and pollinators,” said Steve Buchmann, an adjunct professor in Entomology and Ecology at the University of Arizona who specializes in insect/plant interactions and who has researched bees extensively. To entice bumblebees to visit your garden, “plant mints, Salvia, Monarda, plants in the sunflower family and clovers,” he advised.
Don’t stop at just planting flowers though, build a nest for bumblebees, too! It’s easy and fun to do. The bumblebee queen seeks out a nesting site that already has nesting materials, such as twigs, grasses, straw, moss and other garden debris in it. This is why abandoned nests of birds or small mammals are often selected as bumblebee nesting sites. Gardeners who are too tidy about garden debris may actually inadvertently deter bumblebees from nesting in their yards.
Bumblebees also prefer a nesting site that is in a full to partial shaded location, which is not frequented by people or pets. The queen bumblebee needs to visit about 6,000 flowers to attain the nectar she will need to arrange her nest, lay her eggs, so a bumblebee nest needs to be located near plenty of flowers.
An easy way to give bumblebees shelter is to leave old bird nest boxes or bird nests in place for bumblebees to move into. You can also make bumblebee nesting boxes with wood. A bumblebee nesting box is very similar in construction to a bird nesting box. Usually, a bumblebee box is 6 in. x 6 in. x 5 in. and the entrance hole is only about ½ inch in diameter or less. A bumblebee nesting box will also need to have at least two other smaller holes near the top for ventilation. These nest boxes can be hung, set at ground level, or a garden hose or tube can be fixed to the entrance hole as a faux tunnel and the nest box can be buried in the garden. Be
sure to fill it with organic nesting material before putting it in position.