In the dark before dawn it sounds like rain falling on the window but it isn't. Instead, it is the sound of dozens of wasps flying against the glass, attracted to the bright light of the kitchen within. Looking out, I see a multitude of yellow triangles, each one with three small dots of black, below which hangs a series of black and yellow bands; a head separated from its body by the inky black background against which I see them fly.
These wasps have, no doubt, come from the nest in the attic space above the kitchen, accessed via a gap in the barge board. Last thing at night, when I let the dogs out, I can see the rigid-legged forms of the sentries that guard the nest entrance. The stragglers in, the nest shuts up shop for the night.
It must be the the timing of the light, coming as it does just before dawn, that triggers a response from the wasps. It does not happen in the dark of these late autumn evenings so there must be some form of calibration going on within each wasp, a trigger that leads to the expectation of the coming dawn and which, ultimately, allows the kitchen's artificial light to trick them into emergence. I suspect that somewhere work has been done on the emergence patterns of wasps in relation to daylight but I have not yet stumbled across it. It would be interesting to know how the response is triggered and managed. For now, however, it is enough to witness this strange spectacle.