Last updated on September 21st, 2023 at 12:36 pm
When you think of bees, you will probably immediately think of fuzzy bumblebees, their bums coated with pollen as they jump from flower to flower, or busy little honey bees carrying nectar back to the hive to make into that sweet syrup we all know and love.
The mention of solitary bees seems to throw off our perception of how bees live and grow.
What do they do without a colony to rely on? We try to unravel the mystery that is the lifecycle of a solitary bee.
Species of solitary bees
Honey bees are incredibly popular.
They’re great for backyard beekeeping and pollinating giant growing operations alike, but honey bees belong to the genus Apis, which actually only contains 11 species.
To put that in perspective, solitary bees number roughly 20’000 species worldwide.
Appearances and characteristics of a solitary bee
The common bees we know of have yellow and black stripes, but solitary bees have a vast array of looks. Take orchid bees, for instance.
At first glance these South American insects may resemble flies; their bodies aren’t as hairy and they have a metallic shine, but a closer look will dazzle you with the range of colours they can be.
Like flying little gems they take on colours like sapphires, emeralds, aquamarines, and amethyst.
Bumblebees are easily recognizable from their large, furry bodies, but the teddy bear bee (yes, that’s its name!) is also thickly covered in hairs.
The teddy bear bee is native to Australia, but the UK is home to over 240 unique solitary species as well, including the ashy mining bee with its white and black hair, the long-horned bee with its notably long antennae, and the tiniest of the bunch: the small scissor bee.
Lifecycle of a solitary bee
Given that solitary bees account for the vast majority of bee species, their lifecycles may vary across different species. Consider red mason bees, for instance.
The males typically only live for around two weeks before they die, and the females only last six weeks.
During this time the female will take on several tasks: she must mate, find or create a suitable home for her brood, and collect pollen and nectar.
She will then deposit a pollen-nectar mixture, lay an egg on top, and then cap it off with mud.
The process is repeated until the tunnel is filled with brood chambers, usually about six to eight at a time.
After her duty is complete, the mason bee mum will die, and the larvae are on their own.
The male-only lives for his two weeks to fulfill one purpose: to mate with females.
Find out how to plant the best flowers for Mason bees in your garden.
For example, looking at the carpenter bee life cycle, blue carpenter bees hatch in the summer, lay eggs in the fall, and then hibernate while their larvae grow.
In the case of this particular species, both male and female bees will overwinter in hollow bramble stalks, and will then come out in the spring before dying.
All bees undergo complete metamorphosis, meaning they go through four stages: egg, larval, pupal, and then adult.
Insects that undergo incomplete metamorphosis hatch as a tiny version of the adult form, and will simply grow in size.
The female bee will lay around 20 or 30 eggs, depending on the species, throughout her life.
Each egg will be laid on top of a bed of pollen, so it will have immediate access to food.
After hatching from eggs, larvae appear as small, white worms.
They will feed off the pollen left by the mother bee. As it consumes the food, it will grow until it becomes a pupa.
Solitary bees usually reach this stage right around the winter months.
Pupae tend to appear as young bees but are usually pale white and at this point have developed legs, eyes, and wings, and are starting to grow hair.
Some species, such as mason bees, will build cocoons around themselves to pupate in for an extra layer of protection; the cocoons are waterproof and touch for diseases to get through.
Other solitary bees will simply grow in the chamber they have been laid in without a cocoon.
Come spring the pupal stage is long over and the bees are fully developed into young adults.
The majority of the solitary bee species that live in the UK are ground nesters.
They will dig tunnels straight down and then diverge off paths in which they will create chambers for their brood.
These nesting spots are recognizable from the mound of dirt that is created from digging, with an entry hole in the centre.
Other solitary species will make their homes in hollow tubes, fallen logs, brickwork, stems, and so on.
In species such as mason bees, they will lay the female eggs towards the back of the hollow crevices, and the males towards the front.
Males always emerge earlier in order to ensure that they will have the opportunity to mate with the females; they may even help pull them out of their nests once they begin to hatch.
The other advantage is that if birds get to the nest and they pull out a few larvae to eat, their beaks will only reach the males and the females will hopefully be untouched.
Dead female bees will mean the end of the line for that generation, but if only the males are eaten then the females still have a chance to seek out males from other nests to mate with.
Pollination efficiency and the lifecycle of a solitary bee
During their short lifespan, solitary bees must seek out pollen and nectar quickly to provide food for the offspring they will produce.
Find out what the best plants for solitary bees are.
You may have seen images of honey bees with pollen baskets attached to their legs; they wet down the pollen with saliva to make it sticky and ensure it stays on during the long flight back home.
Solitary bees don’t fly nearly as far from their nests and instead will allow dry pollen to stick to the scopa hairs on the underside of their belly.
Since the pollen is dry, it is easily transferred from flower to flower.
As well, honey bees tend to be meticulous with their pollination efforts and will revisit the same branches on trees to hit up every single flower along the way.
You can encourage solitary bees to enter your garden by planting a range of flora rich in nectar and pollen.
Check out Revive a Bee’s recommended Wildflower Mix and start transforming your garden or wild area into a solitary bee haven.
Solitary bees will jump between different flowers and plants, making them extraordinary cross-pollinators.
The thousands of honey bees required to pollinate a single acre of an orchard can be replaced with only about a hundred solitary bees.
Another advantage to their short life span is that solitary bees will work longer days.
Honey bees can afford to cosy up in the hive until it is warm enough outside to seek out pollen and nectar.
Solitary bees will start earlier in the morning and end their days later at night than social bees in order to collect as much pollen as possible, which means spending more time pollinating plants.