Create A Native Bee Sanctuary
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
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
The minimum temperature for Honey Bee flight is 54º F, however the hardy Bumble Bee can fly at a
minimum temperature of 40º F.
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.
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.
Read More: Favorite Plants For Native Bees
Read More: Early Spring Plants For Bees
Read More: Trees For Bees
Read More: Native Bee Nutrition
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 to July.
Commercially available bumble bee houses are not properly designed and will not help
support bumble bees. You can
watch the YouTube video How To Build A Bumble
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 appropriate 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.
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
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.
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
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.
The following techniques will help you maintain a healthy population and may help to prevent
the build-up of parasites
Read more: Natve Bee Parasites: Wasps
Spores of this fungus germinate within the digestive tract of bees, then they 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 spots. These chalky 'mummies' are highly infectious, and
spores of this fungus often re-infect nests.
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.
If dampness gets into a cell the pollen store can go moldy 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 colored 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 colored 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.
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.
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.
Wisconsin Native Bumble Bees
Native Solitary Bee Nesting