Presets
Playback
Air and odour
Colony behaviour
Disturbance and time
Layers
Model check
The science
What this page is
This page models how honeybees signal danger and how a colony mobilises its defenders. It gives no beekeeping, health or treatment advice, makes no medical claims about bee products, and does not teach how venom is collected. The bucket in the scene is an inanimate disturbance marker. Bees are drawn about nine times too large so that they can be seen, and the pheromone concentration is in arbitrary units (a.u.): real thresholds and release rates are not claimed here.
Alarm signal in the air
When a worker stings or a hive is disturbed, workers release volatile alarm pheromone, of which isopentyl acetate is the best-known component. The page treats the signal as a concentration C(x, y, t) in a well-mixed layer 1 m deep that is carried by the wind, spread by turbulence and lost by evaporation and dilution: dC/dt + u . grad C = D laplacian C - k C + S. The wind u, the effective turbulent diffusivity D (much larger than molecular diffusion) and the loss rate k are sliders; the solver is a second-order flux-limited (minmod) finite-volume scheme on a 96 by 96 grid. The Peclet number u L / D tells whether wind or turbulence dominates; the downwind reach of the cloud is of order u/k and the spread without wind is of order sqrt(D/k). A vertically well-mixed 2D layer is a simplification of a real, three-dimensional and turbulent plume.
Recruitment of defenders
Each bee is a two-state agent: calm or alarmed. A calm bee becomes alarmed at the rate alpha(C) = alpha_max C^n / (C^n + C_h^n) (a Hill function; alpha_max = 0.5 per second, n = 2, threshold C_h set by the slider), and an alarmed bee calms down with time constant tau. Alarmed bees fly towards the disturbance and also release more signal, which is the positive feedback behind a colony-wide response: with enough signal sharing and slow loss the response cascades, with a high threshold or fast fading it stays local. At a constant concentration the expected number of defenders is A* = N alpha / (alpha + 1/tau). All numbers (population of 300 shown, 40 guards, rates) are illustrative picks, and the colony is a toy: real defence depends on temperature, season, genetics, other pheromones and visual cues that are not modelled.
Cost of defence
A worker that stings elastic skin usually loses its barbed sting and dies, so defence costs the colony workers. The counter shows how many bees reached the disturbance and, for an adjustable fraction that sting an intruder, the expected number of workers lost. The fraction is a slider with an illustrative default and not a measured value.
Checks on the page
Four checks run independently of the sliders: the numerical solver against the exact Gaussian solution of a diffusing, decaying puff, mass conservation with wind and decay, the plume centroid moving at the wind speed, and the stochastic agents at constant concentration against the two-state steady state.