On mild March days like today if you are out and about in the countryside or digging around in the garden, you are likely to come across giant, hairy, bumbling bumblebees often bouncing, zig-zagging around and bumping into anything and everything looking decidedly clumsy and cumbersome. These early giants are Queen Bumblebees, awoken from hibernation and in search of a nectar boost and somewhere suitable to make a nest. Just as soon as they appear, they are gone again and it isn’t until some weeks later that we begin to see smaller, worker bees appear in our parks and gardens raiding flower beds. What happens between the emergence of the Queen and the arrival of the workers is one of natures best kept secrets; in those brief weeks, something extraordinary is taking place right beneath our feet.
The Queen bumblebees we see out and about now can be of any number of species; White-Tailed, Buff-Tailed or Early Bumblebees are the most notable to turn up in our urban parks and gardens. The low to the ground, zig-zagging flight is deliberate; the Bees are looking for abandoned mouse holes or similar tunnels (nests have been uncovered some ten feet under ground), perhaps in bare earth or thick tussocks of grass, under leaf piles beneath thick hedges or behind undergrowth on the banks of a stream or beck. Bumblebees will also nest in crevices below and within man-made structures; walls, conservatories, sheds. Some will use bird boxes or old bird nests; most notably the Tree Bumblebee but by no means exclusively. Unfortunately one of the least likely places for a bumblebee to nest is in the purpose build boxes available from garden centres (bees have rarely ever been recorded using one!).
Like birds, bumblebees need to insulate their nests; old birds nests and rodent holes are perfect because there are usually some hairs or feathers readily available. The Queen, once a suitable site has been found, will create a loose ball of insulating material and just like birds, will forage for nesting material if required, in the immediate area. Loft insulation is a firm favourite and bees have even been recorded using the collected fluff from abandoned tumble dryers! Anything that ensures the nest can maintain a temperature of thirty degrees, no matter the weather, will suffice. The name of the Carder bee derives from the old-English word ‘carding’, a term for combing wool prior to spinning; the Carder bee takes great care in using the bristles of its hind legs to neatly ‘comb’ the nesting material and work it into a snug, comfortable hollow ball.
Within this insulated cavity, around the size of a grapefruit, the Queen will meticulously fashion a thimble shaped cup from wax produced by a special gland on the underside of her body, shaping and moulding it with her legs and mandibles before filling the ‘cup’ with honey. The Queen will collect pollen too and fashion this into a pea-size ball, coated in wax. It is in this pollen ball that the queen will lay 16 eggs, fertilised on exit by sperm stored inside her from before hibernation, when she mated with a lucky male. A groove is carefully carved into the top of the pollen ball to hold snugly the body of the queen as she sits, just like a bird, atop the eggs and begins to incubate them. The fine hair on the Queens underside forms a tight seal and helps to keep the eggs warm. The Queen then begins to shiver, expending warmth into the brood below maintaining a constant thirty degrees, even when the temperature outside of the nest could well drop below freezing. Of course, all of this expenditure is heavy on the Queens energy but she has already solved this problem; the thimble shaped pot, tucked beside her filled with high-energy honey allows her to feed and incubate simultaneously. Trouble is, this pot of honey will not last forever and the Queen will need to leave the nest to gather more reserves; she will use her own bodyweight in sugar daily to keep the eggs at just the right temperature. If the eggs cool too much, they will fail and so any refuelling must be swift. The nest should ideally be positioned in close proximity to a supply of flowers, a refuelling could necessitate visiting over 6000 flowers and this is one of the reasons why our bumblebees are having a particularly hard time of things; the decimation of wildflower meadows (down by 98% in the last 40 years), margins and areas of infertile ground where these flowers thrive at the hands of intensive agriculture, soil fertilisation and weed-killing herbicides means that finding any patch of land with a suitable number of blooms this early in the year is, in many areas, nigh on impossible.
After four days, given the right conditions, the eggs will hatch into small, legless grubs. These eating machines will devour the pollen ball and the Queen will need to forage away from the nest for a constant supply of pollen to feed the young. After shedding their skin three times in two weeks, the grubs, now roughly the size of a broad bean, will spin cocoons. Over the course of two weeks, the internal structures of the grubs will dissolve (we are talking nerves, muscles, gut etc) and completely rebuild itself into the form of an adult bee (it sounds almost completely sci-fi!). The emerging bees are entirely milky-white, fluffy and Arctic-like and will stay like this, like ghosts, for a couple of days. All of these first bees are female worker bees, and by the time they have pupated the queen has already laid a new batch of eggs. These early workers now take on the responsibility of rearing the next generation on behalf of the Queen; some will stay in the nest to provide warmth and attention whilst others, now in full adult-colour, leave the nest to gather pollen and nectar to feed to the young. The Queen resigns herself to a life indoors, never to emerge from the nest again. She is fed and cared for by her workers, her children. The egg laying cycle continues and the number of workers increase; they too build wax honey-pots and even wax containers in which to store pollen. In a good year, with workers a plenty, they will even build a wax dome around the nest to aid in insulation. If the temperature inside the nest becomes to great, no trouble; some of the workers will sit by the nest entrance, revving wings at some 200 beats per second to expel unwanted warm air from the nest. Over the course of Spring and early Summer the nest increases in size, the sisterhood (remember, all of the these worker bees are female) expands to hundreds and then comes a sudden change.
Queen bees have the ability to choose the sex of the eggs that they lay; those fertilised by the stored Sperm become female workers and those unfertilised become males. The Queen also produces a pheromone, a chemical signal, which instructs the grubs to become workers. In early July, the Queen swiftly changes tact, laying both female and male eggs. She also ceases to deploy her chemical signal. Without this pheromone the new female grubs begin to develop into future Queens, growing far larger than the worker grubs and taking far longer to mature. Once fully developed, this mix of new Queens and male bees leave the nest. The boys, in typical fashion, spend days on end gorging on nectar rich flowers (often in groups, you tend to notice the males in late summer on large flowers, doing nothing much but lounging around and drinking themselves into a stupor). The pay-off is their relatively short-lived life, emerging in summer and with no nest to return to in Autumn, they live for just a few months before succumbing to the cold. The males, it seems, live for drink and sex. It’s all very stereotypical…
The emerging virgin Queens live an altogether different life. Mating is rarely observed in bees but with males drastically outnumbering the new Queens it is a very lucky bee that gets to procreate. The virgin Queens are accosted almost as soon as they leave the nest, mating just once, the act is swift and once complete, the new Queen heads straight for hibernation. It is assumed that this is tactical; the new Queens avoids being preyed upon by any predators looking for a quick meal whilst also avoiding picking up any unwanted parasites. The transition from emergence into hibernation is so swift, that Queens are rarely ever spotted in the Summer. Early bumblebee Queens will go into hibernation as early as June, other species usually do the same in July or August; either way it’s a long nap, often some eight or nine months.
Back at the original nest, the Queen is now well over a year old. She has stopped laying eggs, the ageing workers have died and the reserves have disappeared. The balding, dishevelled Queen has nothing left to do but succumb to her fate. The nest and dead within are recycled by carrion feasting bugs, grubs and beetles and as if it was never there at all, the nest is earth again.
Next March, the hibernating new Queens will emerge, zig-zagging, bumbling and bashing around, cumbersome and clumsy; only this time we may have a new-found respect for this supermum, this wonder of the natural world. If you should see a Queen in the coming weeks, remember what it took to get her here. Remember the efforts she will go to in ensuring the survival of the next generation. Remember that our gardens, with our blossoms and blooms at this time of year are an increasingly important part of that cycle. Our gardens are often geared towards late Spring and Summer but it is well worth remembering that planting for early Spring colour can be a genuine lifeline for Bees.
My thanks to Dave Goulson, founder of the Bumblebee Conservation Trust, for this enlightenment!