FARMING FOR POLLINATORS # 2
To become truly bee friendly we must integrate both feeding and nesting requirements of bees. We must always remember that there is no, ‘ one fit all ‘ solution. Nesting requirements are different for our native bees ; requirements for bumble bees will be different from ground dwelling native bees and different, yet again, from above ground nesting bees. Solitary bees will nest different than social bees.
I thought the easiest way to approach this subject was to address each factor and then split out to the various groups of native bees. The first factor is that of distance. The European honeybee can fly up to 5 miles in search of food for the collective colony. Our native bees are utterly different. For our bees to be successful the forage, or food, must be within the flight range of the bee.
Believe it or not, the size of our bees dictates how efficiently it can fly from nest to forage area to collect pollen and nectar. Large bees, such as bumble bees, can forage at distances of 1.5 km from the nest. Medium sized bees, such as mining bees, can fly 350 – 450 m from nest to feeding sites. Small bees, such as carpenter bees, can only fly 200 m away from the nest. Our tiniest of bees is limited to 75 m from the nest site. Bottom line – no matter what the size of the bee, all bee populations thrive best when forage sites are close to nest sites.
The next factor we need to zoom in on is nesting sites. 70% of our solitary bees nest underground creating narrow tunnels. The remaining 30 % are above ground in abandoned wood tunnels created by burrowing wood beetles or in hollow stemmed plant material. Bumble bees also have underground nests usually in abandoned mouse or chipmunk burrows or in natural cavities under rocks and tree roots. Even the nest site openings are specific for different bee species. Ground nesting solitary bees prefer bare soil allowing them easy digging vs. bumble bees that prefer thick vegetation hiding their nest entrance.
But how do you know the ideal spots? Sometimes the worst places on a property, or farm, for growing crops are the best habitats for bees. Usually these areas tend to be well drained, sandy or gravelly and hot. Not an ideal site for plant production but ideal for ground nesting bees. Other ideal sites could be edges of wood lots, stream banks and unused land around buildings and ditches. But remember, once an area has been designated as a nesting area there can be no ground disturbances. No digging, no tillage. Also, direct sunlight is needed to warm soil for the nest site, so trimming back trees might be occasionally necessary.
Of course, you can create nesting areas if no natural sites are present. The easiest way is to create a hedgerow or fence row that is pollinator friendly. The overall aim is to provide food from early spring till fall. Native hedgerow choices, especially for bumble bees would be as follows:
serviceberry, willow, redbud, sumacs, plum, all cherries, hawthorn, shrubby indigo bush, raspberry, blueberry, winterberry, black locust and honey, cucumber, red and sugar maple, catalpa, mountain ash, apple, meadowsweet, basswood, rose and tulip tree.
My take away point is that our bees are highly vulnerable. Because of their small size, many bees are not able to fly far to find food. Also, they do not develop large populations because of their nature – they are solitary in life style. Even social bees, such as bumble or sweat bees, require huge amounts of food to maintain their colonies. However, at the end of the breeding season, only the queen will hibernate through the winter and reemerge in the spring. These over wintering queens are the weak link since next years’ colonies depend on their spring emergence. Also, for all our bees, when populations plummet, genetic diversity diminishes and inbreeding occurs.
Their very nature makes them susceptible to human practices. Our management practices have greatly diminished food resources within ideal flight distances. We have eliminated hedgerows, roadside ditches and wild areas near gardens. Natural nesting areas have been eliminated.
So here is where I will mention one word. Patience. If there is no immediate natural nesting areas – create them. If there is no foraging areas within 0.5 mi of these nesting sites – create them. It takes time to establish strong bee populations. Remember that each female solitary bee only raises a handful of progeny so you won’t see an explosion of bees immediately. Remember it will take time for bees to migrate and establish into your area. With time you will be hosting many wild bee species.