Thursday, December 3, 2015

Of Honey Bees, Native Bees and Overwintering Your Garden (Brenda Van Ryswyk): Part 2

This is a continuation of the interview we did with Brenda Van Ryswyk, Natural Heritage Ecologist with Conservation Halton.

Native Bees Need Habitat; They Need Protection 

Studies show that urban and sub-urban areas can be habitat for many species of native bees, so if you have a big backyard, you can have a really positive impact on native pollinators. A study in France showed that the sub-urban area (areas with at least some lawn/gardens) had the highest abundance of both species and individual numbers of native bees (when compared to highly urban areas of all concrete, and intense monoculture agriculture). Any amount of lawn has real potential.

Brenda reports that some species of bee can use cracks in mortar of buildings for nesting habitat or cracks in pavement. In urban areas they need more nesting habitat and a little bit more nectar (too much hard impervious surface is not good).  She points to a University of Toronto study that showed when flowers were added to an area bees quickly appeared to feed on them.

80% of native bees will use soil to nest in, therefore bare ground and soil is vital native bee habitat, "Not everything needs to be covered in grass or vegetation," Brenda says. The other 20% mostly nest in hollow stems, holes and cracks. Brenda suggests that it is easy to help those species by leaving some dead wood in your yard, not “cleaning up” all the old plant stems or purposefully providing hollow plant stem bundles for nesting.
"Simply planting more flowers for nectar is a simple but highly beneficial thing to do. The next best thing to do would be to leave some bare, sunny ground undisturbed for them to nest in," Brenda says.

More random facts from Brenda:
Most of our native bees are solitary. The exception is the bumblebees, they do build small colonies.
Most of our native bees cannot and will not sting.

The solitary bees
 1) have no reason to sting, being solitary! The main reason for stings is defending the hive, since they have no hive they have no reason to sting.
2) Many solitary bees physically cannot sting because they are so small and are to week to pierce our skin.
3)Bumblebees are one of our native bees that can sting, because they do have a colony they will sting if you harm the nest and individuals will sting if you grab and crush them.
4)But it is perfectly safe to observe ALL bees as they are feeding (even honeybees) because “a feeding bee is a happy bee” and when they are feeding they are away from the hive so will not sting unless you grab and crush them (threaten their life)…..(or step on them, if you are barefoot in the lawn).


Overwintering Your Garden

According to Brenda, it is so important that we don’t clean up too much. Solitary bees will nest in old and raised stems (above ground level-tied to a tree of fence post where ants cannot predate the larvae,  or where it is not too moist, and next spring they will emerge). So if you don’t cut anything down this fall, the stems will be available to use. Remember, last year’s dead or standing stems could have eggs in them, don’t burn or compost them. Brenda suggests a height of at least 2 feet is preferable for nesting. If you must ‘clean up’ the garden then leave some stems in a dry area off the ground for one more year to allows any overwintering larva to mature and emerge.

With leaves, rake them into a pile in the corner of your yard or garden—the bumblebees love these piles of leaves or lawn clippings, as well as compost piles for nesting. Don’t disturb the pile. Another tidbit from Brenda: Bumblebees need to have rodents before they nest.  It’s thought that a female bumblebee can smell mice droppings. She’ll go down the mouse hole and take over an old mouse nest!

Leaves are also important for butterflies: the caterpillar will wrap a leaf around itself for protection to spend the winter that way.
Not tilling your ground is also good since native bees need the top eight inches of ground for their larvae to nest in. "Not all areas need to be fully vegetated or mulched," Brenda says. "Watch an area closely and you may see the native bees digging in the ground and laying their eggs."
Often mistaken for ant holes, the native solitary bee nests are three or four times as wide as an ant hole entrance and will be in bare or sparsely vegetated ground that is dry and sunny (and firm enough it won’t collapse in on them as they dig). One site in France where they put up an interpretive display on bees actually had many bees nesting right below the sign! "The high traffic from the visitors killed the grass and the bees seemed to like to nest there right under peoples feet," concludes Brenda.

A note on lawns: If you do not want to grow a garden with flowers then you can make your lawn space more pollinator friendly by adding some clover to it. “Dutch White Clover” grows fairly low to the ground but it produces flowers that all pollinators can nectar on. Another benefit is that it is a nitrogen fixer (it can collect nitrogen from the air and pull it into the ground) thus making it a free fertilizer for your grass! It can dominate a lawn in some conditions but generally after a few years it becomes a mix of grass and clover about 40% clover to 60% grass. Only bad thing about it is you may not be able to go barefoot without watching not to step on pollinators.