Solitary Bee Basics

Not all bees are fuzzy like bumblebees. Not all bees live in groups, or make honey, or centralize their efforts around a queen.  Among the 20,000 species worldwide (that are known), many bees live a life of solitude.  Chief among them, and our subject this week, are mason bees.  America alone has over 3,500 species of solitary bees, which are responsible for pollination on a level that can be, in some cases, far more effective for biodiversity than the efforts of their social counterparts.  

This week, we wanted to geek out and hit ya with some bee facts, and specifically about solitary bees.  Remember last week when we talked about winter garden prep?  Part of not clearing the brush and debris that insulate our flower beds is for the benefit of bees (as well as other helpful insects).  By now it has to be obvious how important bees are to our global ecosystems, the preservation of biodiversity, and the conservation of the balance of nature.

These little bees are prolific pollinators, as they don’t have sacks on their legs to carry and store the pollen on their legs as they move from flower to flower. This means that more pollen gets strewn about in the flight path of the bee.  More pollen everywhere=more plants, and more biodiversity.  In fact, most solitary bee species outperform their honeybee and bumble-y counterparts.  In our learning, we found one article that said with some species of mason bee, a single mason will pollinate 120 times more plants than a honey bee!

Most mason bees nest in tunnels in the ground, or hollow stalks of plants, crevices of rocks or logs, or in narrow holes or tunnels wherever they can find them, usually in close proximity to flowers, fruit orchards, etc.  Species around the world make their nests in everything from snail shells to sidewalk cracks to dried cow pies.  Some species can and will nest in groups close to one another, creating quite the spectacle at certain times of year.  Despite this proximity, they still don’t work together, and go about their bee business as individuals over the course of their lives.  Their life cycle is an interesting one, taking place mostly out of view, in their tiny nest tubes and crevices (more on that in a minute). Their adult lives are brief and are “timed to coincide with the spring blooming flowers,” according to bee expert and conservation biologist Thor Hanson. 

The males of the species live and die for a singular purpose, and that is to mate.  After they fulfill their mission, the males die shortly afterward.  Females have about a month where the conditions are perfect and lay as many eggs as they can.  Orchard mason bee females can produce up to 30 eggs per bee if the conditions are right.  Mason bees don’t produce honey or wax, but they do make something colloquially referred to as “bee bread,” made of pollen and nectar.  This bread is layered in the tunnel of the nest.  A singular egg will be laid on a small ball of bee bread, then sealed with mud, hair, etc. enclosing each singular egg in a tiny apartment of its own, one layered on top of the other.  When the tunnel is full, the female will seal it off with a neat plug of mud, thicker than the dividing walls that separate her babies from one another.  

Though the female doesn’t take any parental role in the life of her young once they emerge, she does guard her nest tunnels when she isn’t actively feeding, up until the point she dies.  (There’s a lot to read about species that prey on the larvae of mason bees, with fascinating adaptations to act as highly specialized parasites and predators to mason bees specifically.  It’s too much to get into for the purpose of our lil’ blog, but definitely worth the learning if this stuff is as fascinating to you as it is to us.)  

From there, the larvae spend months in the nest, slowly sustaining themselves off the bee bread.  As they feed, they spin and seal themselves off in these tiny little cocoons.  Come springtime, the larvae pupate and begin to emerge from their cocoons and have to chew their way out of their tiny studio apartments, to emerge a fully grown bee.  

What’s so fascinating about their nesting habits is that behind the plug of mud that often seals the end of the tunnel, the females often leave the forwardmost chamber empty, in anticipation of potential predators. Furthermore, females have the ability to predetermine the sex of their offspring. (Hanson)  Isn’t that wild?! They can choose whether their babies will be male or female!  Female mason bees have the ability to store sperm from males after they’ve mated in a pouch near their ovaries, and strategically fertilize the eggs at the back of their tunnels, and not the eggs in the cells at the front of their tunnels.  This means, generally speaking, that the males are more expendable to the species than the females are. This also means that fertilized eggs produce females, and unfertilized eggs become males.   

The females knowingly lay eggs and fertilize them at the back of the chamber, dedicating more bee bread and more layers of security, essentially, against predators.  Thor Hanson also points out “...For male bees, it offers only a shrug of cold logic: so long as enough of them survive to breed, the population can afford to lose the rest.”

Nature, you crazy.

All this is merely the tip of the iceberg.  Bees are endlessly fascinating, and we obviously want to encourage you to seek out more information about these beloved and necessary creatures wherever you can.  We particularly love Thor Hanson’s book Buzz, which is a sciencey read without being dry.  We also just started carrying cardboard tubes to make your own bee houses.  We will also be teaching a class on how to make your own bee house in the near future.  You’ll get to make, and take home your very own bee house, and we’ll even send you home with a small number of live mason bee cocoons, and instructions for how to set them up to hatch happily and healthily come springtime.

Hopefully we’ve piqued your curiosity enough to keep learning more, or at least entertained you with some interesting facts about bees that you didn’t already know.  In the arena of loving plants, and nature, and our planet, we thought it fitting to shine a spotlight on Mother Nature’s small and mighty; the solitary bee.

Cheers, y’all. Buzz off and go read more about bees! (And sign up for our class when we post it!)