A while ago, a graduate student from the University of Connecticut asked us if he could include LaGuardia Corner Gardens as a site for his study of solitary bees in urban and non-urban areas. After confirming that this research would neither harm bee populations nor gardeners, we were happy to support it.
A couple of weeks ago, Matthew and his undergraduate assistants Maddy and Emily came to the garden to check out the situation. They monitor sites all over the city and were very happy to report that our garden has a lot more bees than Central Park!
Here, we are not talking about honey bees or bumble bees that live in hives or colonies with a queen and many workers. This research is about wild bees where each female makes her own nest. These nests can be in the ground, inside of hollow plant stems, in holes in wood or even in cracks in walls. The size of solitary bees ranges from very tiny to relatively huge. None of them sting unprovoked. They don’t have a hive to protect and can afford to be less aggressive than honey bees (at this time of the year, honey bees also only sting when they feel threatened).
On this day, the researchers were particularly interested in the large carpenter bees that visited our flowers in sizable numbers. Matthew, Maddy and Emily captured bees with their nets, gently put them into a little container, painted a green or pink dot on their backs (green for males, pink for females), and let them fly off again. The colored dots were meant to avoid collecting the same bee more than once. From females, Matthew took a small sample for genetic testing. This way, he and his team can learn about the genetic diversity of the different populations they study. The bees were mostly unfazed but clearly weary of the net when it got near them for a second time.
How does one distinguish male from female carpenter bees? This is really easy: females have a black face like the one in the photo above. Males have a white face. The left bee in the net is a male.
There were also other solitary bees out and about: we saw some tiny masked bees and the first males of our resident leaf cutter bees. Female leaf cutters will emerge a little later. Below is a male on a milkweed flower. The photo was taken last year in June, milkweed is not blooming yet.
Unfortunately for the solitary bees, last week was rainy, windy and unseasonably cold. Not the best conditions for finding a mate, collecting pollen and building a nest.
Solitary bees can’t fly long distances like honey bees and they don’t have any honey provisions either. This is one reason to plant as many flowers for them as possible. Those are flowers that produce abundant nectar and pollen. This means plants with single flowers instead of flowers with lots of petals but no stamens, e.g. lacecap instead of mophead hydrangeas and single instead of pompom chrysanthemums. Of course, we still love our blue hydrangeas, roses and peonies, but we add some native asters, goldenrod and bee balm to the mix.
