Bees grow through four distinct stages: egg, larva, pupa, and adult. The entire process takes about three weeks for a worker honey bee, and what happens during those weeks is remarkable. A tiny larva weighing 0.1 milligrams balloons to around 120 milligrams in just six days, meaning the finished bee weighs roughly 1,000 times what it did as a newly hatched larva.
From Egg to Larva
A queen bee lays a single egg into a wax cell inside the hive. The egg is tiny, roughly the size of a grain of rice, and stands upright on the cell floor. After three days, it hatches into a larva: a small, white, grub-like creature with no legs, no eyes, and no wings. At this point the larva does essentially one thing: eat.
Young worker bees called nurse bees immediately begin feeding the larva. For the first three days, every larva in the hive receives royal jelly, a protein-rich secretion produced by glands in the nurse bees’ heads. After those initial three days, the diet splits depending on what the colony needs. Larvae destined to become workers get switched to a mixture of royal jelly blended with honey and beebread (a form of processed pollen), while larvae being raised as queens continue eating pure royal jelly in large quantities.
This dietary switch has massive biological consequences. Beebread and honey contain a plant chemical called p-coumaric acid that royal jelly lacks entirely. When larvae consume it, the chemical alters the activity of roughly two-thirds of the bee’s genome, turning some genes up and others down. The result is a completely different body plan: workers end up smaller, with underdeveloped reproductive organs, while queens grow larger and fully fertile. The higher sugar content in the queen’s diet also acts as a feeding trigger, causing queen larvae to eat more and grow faster, which sets off a cascade of hormonal changes that lock in their development as queens.
How Larvae Shed Their Skin
Because insect larvae have a rigid outer covering (an exoskeleton) instead of an internal skeleton, they can’t grow continuously. Instead, they grow in bursts. A honey bee larva molts four times during its feeding period, each time splitting out of its old skin and expanding into a slightly larger new one. These molts are triggered by pulses of hormones that signal the inner layer of skin to separate from the outer shell, build a new covering underneath, and then shed the old one.
After the fourth molt, the larva reaches its fifth and final larval stage. At this point it has eaten enough to fuel the next transformation. Nurse bees detect chemical signals on the larva’s surface and respond by sealing the cell with a wax cap. The larva is now sealed inside, alone in the dark, and ready for the most dramatic phase of its development.
What Happens Inside the Sealed Cell
Once capped, the larva spins a thin cocoon around itself and enters the pupal stage. This is where the grub essentially rebuilds itself into a bee. The soft, legless body reorganizes its tissues to form wings, six jointed legs, antennae, and compound eyes. Hairs develop across the body. The internal organs restructure for adult life. It’s a process similar in principle to what happens inside a butterfly chrysalis, though bees don’t dissolve quite as completely.
The compound eyes are among the last structures to fully form. Late in pupal development, genes involved in building the eye’s thousands of individual lenses ramp up to ensure the bee will have functional vision the moment it emerges. As the pupa matures, its body gradually darkens from white to its final coloring. Wings finish forming. The new exoskeleton hardens.
Temperature Makes or Breaks Development
None of this works without precise temperature control. The brood nest, where developing bees are clustered, needs to stay close to 34.5°C (about 94°F). Worker bees maintain this temperature with less than 1°C of daily variation, even when outside temperatures swing from well below freezing to over 100°F. They generate heat by vibrating their flight muscles and cool the hive by fanning their wings and spreading water droplets.
Even a degree or two of deviation can cause serious problems. Brood raised at temperatures outside the 32 to 35°C range (roughly 90 to 95°F) may develop abnormally, and very few bees successfully emerge below 28°C (82°F) or above 37°C (99°F). Temperature control is so critical that nurse bees tend capped brood cells around the clock, pressing their bodies against the caps to warm the pupae inside.
Emerging as an Adult
When development is complete, the adult bee chews through the wax cap of its cell and crawls out. For worker bees, this happens about 21 days after the egg was laid. Queens develop faster, emerging around day 16. Drones (males) take the longest, at roughly 24 days.
A newly emerged bee is soft and pale, with a body that hasn’t fully hardened yet. Over the next several hours, the exoskeleton firms up and the bee takes on its adult coloration. Workers start their adult lives inside the hive, spending their first one to two weeks as nurse bees tending brood before gradually transitioning to other jobs like building comb, guarding the entrance, and eventually foraging. A newly emerged queen has additional maturing to do: she spends five to eight days in the hive while nurse bees feed her, allowing her reproductive organs to develop and her flight muscles to strengthen before she leaves on mating flights.
How Solitary Bees Grow Differently
Honey bees get most of the attention, but the majority of the world’s roughly 20,000 bee species are solitary, meaning each female builds and provisions her own nest without help from a colony. Their growth follows the same basic egg-larva-pupa-adult sequence, but the timeline and setting look very different.
Leafcutter bees and mason bees nest in hollow cavities like plant stems or holes in wood, dividing their nests into individual cells separated by mud or leaf pieces. A female stocks each cell with a ball of pollen and nectar, lays a single egg on top, and seals it off. The larva hatches, eats the food supply its mother left behind, and then enters a long resting phase. Many solitary bee larvae overwinter in their cells, not pupating until the following spring. Adults emerge for just a few weeks in late spring or summer, mate, provision new nests, and die. Carpenter bees follow a similar pattern, boring tunnels into soft wood and stocking cells for their young, with the new adults hibernating through winter inside the nest.
Digger bees take the process underground, excavating tunnels in soil and packing cells with pollen and nectar for their larvae. Like other solitary species, the larvae develop slowly, spending months in the ground before pupating and emerging as adults for a brief active season. Without a colony to regulate temperature or nurse bees to provide food on demand, solitary bee larvae depend entirely on the provisions their mother sealed in with them and the insulating properties of their nest site.