Native Bees Are Your Benefactors

When you hear the buzz, give a nod of thanks!

Sweat bee.Sweat bee.

Bees are just vegetarian wasps, to paraphrase Dr. Robbin Thorpe.  But to oversimplify the role and life habits of bees would be not only a disgrace to hymenopterists, but also an insult to the 4,000 species of bees in North America and the 20,000 species of bees found worldwide. Bees of any stripe are so much more than just a subset of a larger hymenopteran group and pigeonholed to one diet.  We have bees of every range of size, color, shape and habitat.  Fiery reds, metallic and iridescent blues and greens, bright yellows and any combination of these make for a spectacular visual.  From tiny digger and sweat bees to large bumble and carpenter bees, bees have it covered.

Bees are classified as Hymenoptera (membrane-winged insects): From the Greek Hymen-membrane; -ptera – wing. They are close relatives of wasps, placed in the Apocrita suborder.  True Bees, what we will be examining today, are in the clade Anthophila.

When one hears “bees” one might instantly think of the Western Honey Bee, Apis mellifera, with good reason. The Western Honey Bee has been introduced worldwide (No, they are not native here in North America) and we are familiar with the benefits of honey and wax that we take from them, along with the pollination they provide.  Western Honey Bees, while extremely interesting in their own right, are just one species within a much larger group of animals.

Of the bees native to North America, 90% are solitary and nest in the ground or hollow stems.  Meaning, they do not have large colonies or build in large voids such as tree hollows or walls.  Female solitary bees dig their own burrows (or find an old beetle tunnel in a tree limb), provision the egg with a ball of pollen, and seal the cell.  She will continue to do this until she is out of eggs or the season, for her, is done.  One of the best things about the majority of those solitary bees is that they really do not sting!  Even if they were the slightest bit aggressive, they do not have a stinger long enough to cause any damage.

Many families of ground-nesting bees, like Andrenidae (miner bees) or Colletidae (cellophane bees), have a site preference, so it seems as if there is one large colony of bees.  They are aggregate nesters, meaning they are fine being near their own species, but they do not enter each other’s’ nests.  If you look closely, and you can get close because they are harmless, you can see each bee is orienting to, or going in a different hole in the ground.  The females prepare the nesting areas by digging a tunnel in the ground or cleaning out the stem, then lining the burrow with a cellophane-like substance they produce, or small pieces of leaves or petals.  Then the nest is ready to be provisioned and for the eggs to be laid.

Other bees that nest in hollow stems or beetle burrows may seem to be “more” solitary, but their nesting preference may not provide adequate nesting space for many females in an area.  They have the same pollen ball and one-egg-per-cell behavior as the ground nesters.

Bumblebee. Photo: Jeff Beane/NCMNS.Bumblebee. Photo: Jeff Beane/NCMNS.

Because of their pollen-as-food ways, you should be thanking native bees for your successful harvest of melons, squash, blueberries, and even tomatoes.  For example, if not for the burly bumble bees (Bombus spp.) with their buzz pollination, your tomatoes would not successfully produce fruit.

The great majority of bees, being solitary, are quietly pollinating your fruit and flower gardens, while getting none of the credit.  Many of the native flora are much too large, or much too small, for the typical honey bees to pollinate effectively.  Look at the flowers of mint, or oregano, that would take a small sweat bee to pollinate properly.  Every year when I let my basil go to seed, I can sit and watch small sweat bees getting their fill of nectar while spreading the pollen from flower to flower.  As a matter of fact, most native bees are out earlier in the spring and later in the fall to perform most of the pollination that honey bees would not be able to do.

And mentioning the effective pollinators, there are just 49 species of bumble bees in America north of Mexico.  They are all within the genus Bombus, but unlike most other insect groups, are more diverse in the northern temperate and mountain regions.  Bumble bees received their common name not for their “bumbling” way of flying – they are really quite adept flyers – but by the buzzing noise they make when flying.  Although, their bodies do seem to be too large for their wings to carry them.  In fact, a modern myth is that by aerodynamic calculation of the body size and surface area of the wings, bumblebees were incapable of flight. Though this myth has persisted for decades, it was the result of the erroneous assumption that bees fly like fixed-wing aircraft. [See https://www.nature.com/articles/521S64a for example.]

And last, but not least, the solitary and unfortunately demonized Eastern Carpenter Bee, Xylocopa virginica.  One of 10 carpenter bee species found in North America, the Eastern Carpenter Bee is not primarily a pest, as many would like to think, but an efficient pollinator as well as a host.

Carpenter Bee. Photo courtesy of Elsa Youngsteadt.Carpenter Bee. Photo courtesy of Elsa Youngsteadt.

Eastern Carpenter Bees are generalist pollinators that follow flower constancy, meaning they will go to one type of flower repeatedly until the nectar and pollen is depleted.  Once picked dry, they will move onto another type of flower.  This is one reason why they are such effective pollinators – they stick with the same flower, and hence, have only one flower species pollen on their bodies.

Carpenter bees are often confused with bumble bees with good reason.  The average bumble bee is approximately the same size as a carpenter bee, and both have similar aposematic (warning) coloration.

But telling the difference is really quite easy: Bumble bees have fuzzy butts, while Carpenter bees have shiny butts.  Another characteristic that will help is identifying the male Carpenter Bees from females.  Male Eastern Carpenter Bees have a yellow spot on their face; females do not.

Female Eastern Carpenter Bees, being solitary and like so many of the other native bees, do not want to risk injury, or worse, to themselves, in trying to sting you.  They want to gather resources for their offspring.  They will only sting as a last resort in self-defense in order to escape.

While it may seem the damage from their tunneling nest-making is bad, Eastern Carpenter Bees , the tunnels they make typically only cause cosmetic damage.  The trade-off is the amount and efficiency of pollination by these bees.  Plus, they usually only tunnel into and build nests in older wood, so it may be time to replace some boards on the deck if you are seeing them buzzing around.

So when you are out walking and appreciating blooms any time of year or even tending your garden, give a tip of the old sun hat to the non-honey bees you see around.  They deserve a lot more love and respect than they receive.