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Wild Bees: Create A Native Bee Sanctuary

The time is now!

Homeless bee cartoon Wild bees need our help. Many populations are declining due to habitat loss, disease and pesticide poisoning. Domesticated honeybees managed for honey production and agricultural services are also struggling.

As our most important pollinators, bees provide one-third of the food we eat. They also allow wild plants to reproduce and produce berries, fruits and seeds. Bee losses pose a risk to our life support systems.

Each of us can create habitat to support local bee populations. Bees are more likely to thrive in your backyard, community or patio garden and on mixed farms than on acres devoted to single crops. Urban settings mean short flight paths and a variety of different plants and flowers to sample.

Bees Emerge In Spring

Of the at least 438 species of bee species in Wisconsin, about 33% emerge between March and April and are critical for pollination of a number of native plants and tree fruit crops.

When spring-time comes, and temperatures reach 55° F or warmer, the solitary bees will emerge from their nests and start finding pollen for their offspring. In one nest of mason bees there are usually 5-8 bees. The front 2/3 is normally males, and the back 1/3 is females. Once the temperature warms up to 55° F the males will begin to emerge from their cocoons first. The bees must chew their way through the clay that was placed inside the tube by their mother until they reach the opening of the tube. A few days later the female bees follow by emerging from their cocoons and chew their way out.

For our summer-time bees they will emerge later in the season when day time temperatures reach a consistent 70° F. Leafcutter bees will usually emerge in mid June-July.

Bumble Bees Are The Exception

Commercially available bumble bee houses are not properly designed and will not help support bumble bees. If you are interested in building a Bumble Bee nesting box, check out the Bumble Bee House Plans. You can also watch the YouTube video How To Build A Bumble Bee House

Types Of Wild Bee Houses Bamboo Stakes Bee House

Bundle of Sticks: The simplest type of bee house is the bundle of sticks model. Pretty self-explanatory: just take some number of hollow sticks or reeds, bundle them up, and put them out where bees can find them. Usually, the bundle will be contained in some sort of shelter to keep the sun and rain off, but you can put out plain sticks tied up with wire, too.

Bundle of Bamboo: Bamboo is a popular material for its availability and durability. Bundles of first-cut bamboo stakes can be ordered in bulk from garden stores and cut into appropraite lengths for bees. Phragmites is easier to cut than bamboo, but harder to obtain. If you have the right plants, you can even collect dead stems from your garden in the fall or spring for a bee house. Raspberries, bee balm, Joe-Pye weed, cup plant, sumac, certain asters, or anything else with a large hollow stem provides good nesting places for bees.

Wood Block: A slightly more advanced type of bee house is the wood block model. This design mimics the holes in trees that cavity-nesting bees will use in the wild. It is simply a block of wood of any size with some deep holes drilled partway through it (this will require a power drill and a very long bit). At that point you could be done, and bees would nest in it, but there are several problems with that. The tunnels in this case are even less accessible than the bundle of sticks, making the block very difficult to keep clean and the bees inside impossible to see. Perhaps the main disadvantage of the wood block model is the lack of variety in tunnel diameters compared with the bundle of sticks. With too little variation, the nest will not attract as many different kinds of bees

Observation Block: The most complex type of bee house, but the best in terms of convenience, is the clear-topped wood block or observation block. It is similar to other wood block nests, only instead of drilling holes, you use a router to cut U-shaped grooves in the outer face(s) of the block. These grooves are then covered with a transparent lid to make a tunnel for bees to nest in. The nests can be easily seen without opening them, so you can even watch the bees at work during nesting season and monitor their progress. When cleaning is needed, the lids can be removed for easy access to the interior, then replaced when they are ready to be used again.

Tips For Making Bee Houses Bee House With Larvae

Paper Straws: Insert disposable paper straws into each tunnel. These can be pulled out to access the bees, and easily be replaced with new straws to keep pathogen levels down. Because drilled holes will all be of uniform size, the straws can be cheaply purchased in bulk or even rolled yourself. Glass or clear plastic tubes may be used instead of paper in order to easily see inside, but this is not recommended except perhaps in very arid places. Glass and plastic do not absorb moisture, creating a damp environment that will facilitate mold growth. Bees will have greater nesting success in paper.

Tunnels should be open on one end and closed on the other end. Being open on both ends increases exposure to parasites and pathogens. If using a bundle of reeds like bamboo, cut the segments so that one end is closed by a natural node.

Ideal tunnel depths are between 5 and 8 inches, and diameters from 1/8” to 1/2”; you do not need to be very exact. Variation in tunnel dimensions accommodates more bees of different species and sizes, and also helps bees distinguish their nest from others nearby and remember where it is. If all the tunnels look the same, the bees may become confused and lose track of their nests.

It should be obvious, but do not use treated wood or aromatic insect-repellent wood (such as cedar) for nest blocks.

If you are making clear-topped wood blocks, get high-quality wood with as few knots as possible, as knots can weaken the walls between adjacent tunnels. Going across the grain also weakens tunnels.

To create more nest variation to help the bees orient themselves, paint the tunnel entrances different colors. Blue, black, and unpainted raw wood make a good contrast. Keep in mind that bees cannot see reds.

Bright, fluorescent blue is highly visible and attractive to bees. Painting parts of your nest or shelter box this color might attract more bees from longer distances.

Tips For Setting Up Bee Houses

Mason Bee pollinating a flower

Bee houses must be clean! If you are re-using a house from last year with bamboo tubes, replace all the tubes. If you are using wooden trays, brush off all debris on both sides. If you found Chalkbrood, clean the trays with a 50% solution of bleach and water. You can also clean wood blocks using a bleach solution during winter cleaning to prevent build-up of disease. Mix a half cup of bleach per gallon of water in a covering the surfaces with the solution, rinse, and then dry.

Bee houses should be around three to five feet above the ground. Individual stick bundles or wood blocks can be hung up using wire, while metal garden stakes with wood screws work well for holding wooden shelter boxes.

Watch out for ants and spiders. Keep approaches to the nest lubricated with petroleum jelly, tanglefoot, or a similar product; this makes it difficult for ants and spiders to keep their grip. Keep the immediate area around the nest clear of tall grass and weeds so ants and spiders cannot climb up directly onto the nest. However, nothing is foolproof, and especially in wetter, more thickly grown patches, you will usually need to remove ants and/or spiders that find their way in.

Ideal locations are recently disturbed, weedy fields in the process of reverting to a more natural state. Abandoned lots, overgrown gardens, railroad right-of-ways, and recently cleared trees are all good bets. Place the nest in a dry spot with low vegetation, if possible. Mason bees need a nearby mud source, but don’t put the nest right on top of it.

Most importantly, make sure there are flowers available throughout the spring, summer, and fall. Ideally, there should be several species blooming at any given time. Maintaining a “pollinator garden” nearby is always a good idea. In addition to flowers, you can also harvest stems for bee houses.

If possible, put the nest on the eastern side of a tall obstacle such as trees or a building, so that it will receive warm sunlight early in the morning, but be shaded from intense afternoon heat. The nest entrance should face southeast to get more early morning sun.

Bee House Management

The following techniques will help you maintain a healthy population and may help to prevent the build-up of parasites

Fungus: Chalkbrood, Ascosphaera apis

Spores of this fungus germinate within the digestive tract of bees, then begin mycelial growth during the last instar of larval development. Dead larval and pupal bees appear chalky thanks to growth throughout the bee of mycelia. Dead larvae are chalky white and usually covered with filaments (mycelia) that have a fluffy, cotton-like appearance. These mummified larvae may be mottled with brown or black spotsThese chalky 'mummies' are highly infectious, and spores of this fungus often reinfect nests.

Parasite: Cacoxenus indigator

Bee House This is a very small fly with red eyes that you may see around your Red Mason Bee tunnels. The larvae of these flies eat the pollen store and the young bee larvae in the Red Mason Bee's cells. They remain as pupae throughout the winter and the adult flies emerge in spring, using the small holes in the mud walls to escape. They are the most important biological factor in the reduction of Red Mason Bee populations.

In late summer or autumn you should examine all the tubes that have been walled-up with mud during the summer and identify any in which there is now a small hole. These have been taken over by the fly, and these tubes or tunnels should be cleaned out and the contents destroyed.

Identify Bee Larvae Death

If dampness gets into a cell the pollen store can go mouldy or the bee larva or pupa itself can succumb to fungus diseases. Also bee larvae can be killed by wasps, or by invasions of pollen mites that eat the pollen store so that the bee larva starves.

During winter, after removing the contents of any tunnels that have fallen prey to the Cacoxenus fly, mark all sealed tunnels with a coloured marker pen. This will not harm the emerging bees next season as they do not ingest any of the mud wall of each cell, they simply break it up to get out. At the end of next season (i.e. next September or October), any tunnels that still have the coloured mark represent those from the previous year in which the bee larvae died and did not emerge. These should be cleaned out, or in the case of bamboo or cardboard tubes, removed and destroyed.

Protect Houses From Winter Wet

Bee House You can remove the occupied logs and tubes and keep them in a cold dry place during the winter, to protect them from winter wet, replacing them in the bee house in March. An unheated shed, porch, or carport will do. This is very important – winter wet, not cold, is their enemy. Do not store in a warm place – they need to be cold but protected from persistent heavy rain during the winter.

Persistent wind-blown rain can dissolve the mud walls of the cells, and cause both wooden blocks and cardboard bee tubes to rot, and the young bee pupae will succumb to fungus diseases. If your bee house has a good overhanging roof and is completely rainproof you can leave the tubes there during autumn and winter. From April onwards, young bees that have over-wintered in a dormant state inside the tunnels will emerge, and start the cycle over again.

Beware Birds

If you notice Woodpeckers or other birds attacking the tunnels looking for bee larvae, fix a piece of chicken wire across the front of the bee house. This does not seem to deter the bees.

Further Information

Mason Bees
Where Do Native Bees Go In Winter?
How To Help Bumblebees