The plight of the European honeybee is well-publicized: our most popular pollinator is perishing in pandemic proportions. This is a major cause for concern across North America, for honeybees play a major agricultural role in our food system. Honeybees are only one species among thousands of native pollinators, however, which are also threatened due to habitat loss, monocultural cropping, and chemical pesticides. Native bees also play a part in pollinating agricultural crops, but because they are solitary and not easily "farmed" the way honeybees are, they receive much less media attention.
It is so very easy (and fun!) to support native bees. I'll show you one way to draw more of them to your home, with just a handful of household tools and free pieces of wood you find lying around.
Why it's important to help all kinds of bees
There are about 4,000 species of native bees in the United States alone, according to the USDA. All of these different bees fill specialized job descriptions for pollinating various flower types with which they co-evolved. For instance, long-tongued bees can dip their tongues into flowers with elongated shapes, while short-tongued bees perfectly pollinate open, daisy-like flowers. Some bees "buzz pollinate" by rapidly moving their wing muscles when they land on a flower, to shake pollen granules out of the anther tubes. Cranberries, blueberries, tomatoes, and other nightshade (Solanaceae) family plants require buzz pollination by bumble bees and other native species able to use this technique. Without the right pollinators, some specialized plants would have no way of reproducing.
Native bees are also often much more efficient pollinators than European honeybees, because they are messy. A mason bee collects pollen all over the bottom of its abdomen. It lands on a flower and gets to work collecting nectar, while pollen attaches to the hairs on its belly. Meanwhile, other pollen grains from previously visited flowers drop off, and voilà, the job is done. Honeybees, on the other hand, are more fastidious. They collect pollen in special pollen baskets on their hind legs, by cleaning themselves off and packing errant pollen grains into their saddlebags. This technique means that less pollen is exchanged between flowers.
In order to retain the rich biodiversity around us, we need to support both sets of partners in this beautiful relationship. We do this by offering space to our native plants, and providing nesting, shelter, food, and water to the bees.
A wasp visits a yarrow flower.
Eastern carpenter bee pollinating a lavender flower.
A honeybee out on an early spring day. Note the orange pollen neatly collected in pollen baskets on its hind legs.
Bee hospitable: build a bee hotel
There are many different kinds of bee houses, or bee hotels, that you can set up around your home. They range from homemade log cabin equivalents to store-bought Hilton hotels intended to house many sizes and species of solitary bees.
To build a simple bee hotel, you will need:
a chunk or block of wood, at least 6 inches, preferably 7 inches deep. *Make sure not to use pressure treated or other chemically treated wood.*a drill with drill bits ranging from 2-10mm (most common sizes in inches are 1/8" to 5/16")Mounting screws or nails(optional, if needed) overhanging board providing 2-3" of overhang at front of blockDrill holes on one side of the block of wood, with sufficient space between that you are in no danger of drilling into neighboring holes. If you have a drill press, it can help to keep your holes parallel to one another. For larger diameter holes (5/16"), use 6-inch long drill bits if you have them. This is the preferred depth for mason bees, which lay a proportion of male and female eggs based on the depth of the hole. Holes that are too shallow don't leave enough room for a full complement of males and females.Do not drill all the way through the block. Bees prefer nesting holes that are open on only one end.Make sure to sand or smooth the hole openings to clear away splinters. Bees will avoid holes with sharp splinters because they can damage their wings.Once you have your holes drilled, attach your bee house to the side of your house, a fence post, or some other vertical surface. Face the openings to the south or southeast, where they will receive morning sun. Bees like to emerge in the morning and bask in the sun to warm up before they fly out to eat and gather stores.To help keep bee larvae dry, you can attach some form of an overhang above your wood block. It should form an eave of 2-3 inches.
Native bees will readily use nesting holes drilled in wood blocks. Holes packed with mud show which ones have bees in residence.
A solitary bee rests in a nesting hole.
Native bees nesting.
Mason bees come and go from this purchased bee house. Note the bright yellow pollen covering the abdomen of the bee entering its nest.
Attracting bees and maintaining your bee abode
There are several things you can do to provide a healthy habitat for your native bees:
Put up your house in late winter/early spring to attract mason bees and orchard bees. They emerge early (when temperatures reach 50º F or thereabouts) and have a short adult life. Leafcutter bees will emerge later in the summer, though, so don't worry if you put it up a little later.Include native plant species in your gardens to attract solitary bees and other native pollinating insects. Use straight species rather than cultivars to be sure you are providing the best possible forage sources (read my article on species and cultivars for more on this).Provide a source of mud, preferably high in clay, for the bees to use as nesting material. This might mean keeping a small area of bare ground somewhere close by and running the hose on it regularly, or putting out a tray or shallow container with soil that you keep moistened.Make sure your bee house is in full sun for at least part of the day. Bee houses positioned in shady areas can attract parasitizing wasps, which prey on the bees.If you use a drilled block of wood with holes that cannot be opened and cleaned, replace your bee house every other year, to reduce chances of disease. Don't just chuck your old block, however, until all of the bees have hatched out of it (should be by late summer of the second year).
A note on Hilton-style bee hotels
Some people buy or build bee hotels that are quite large, with nesting tubes of all sorts and sizes. The jury is out on whether these ultimately help or hinder native bee populations. Native bees are solitary, and do not naturally congregate in large numbers in tight quarters. Furthermore, they do not tend to share housing with bees and wasps of other species. Large mega-hotels such as the one below that offer large diameter holes may attract more predatory wasps, and may promote the spread of infectious diseases among the native bees that use them. Plus, they still require maintenance to ensure that the residents have clean, healthy nesting holes. With this number of residences, maintenance could become quite a chore!
A large bee hotel. Photo credit: Ong-Mat, Flickr.
For further reading
For more information about native bees, check out the publication below from the USDA Forest Service and Pollinator Partnership. It has beautiful illustrations and a lot of fascinating information about various North American bee species.
Have fun putting up your bee hotel! Let me know how it goes.