No wind is expected on this Monday, yet in gardens and fields, long white threads continue to flutter and shimmer in the sunlight. These silk filaments, produced by tiny spiders, appear to defy the weather. Their secret lies not only in the wind but in a much more subtle force present permanently in the atmosphere. This mystery, which combines biology and physics, is especially relevant now, as autumn favors the appearance of these famous threads. The threads of the virgin are produced by young spiders, particularly those of the genus Erigone, which practice "ballooning" to colonize new territories. Researchers from the University of Bristol have shown that the atmospheric electric field allows spiders to take off even without wind. This phenomenon of passive flight, sometimes called "aerial plankton," also concerns other species such as caterpillars, butterflies, and mites, and promotes the dispersal of populations. These white threads floating without the slightest breath of air are attached to grasses and plants and have a name: the threads of the virgin. They appear especially at the beginning of autumn, when young spiders, particularly those of the genus Erigone, seek to colonize new territories. For this, they use a technique called ballooning: they release a silk thread that propels them into the air, sometimes over hundreds of kilometers. The phenomenon can involve thousands of individuals at the same time, who often drift together, forming these visible sheets on sunny and mild days. This journey is not trivial. Many spiders do not survive this attempt, carried by the wind to unfavorable environments such as the sea. Those who successfully land release their thread, which has become useless, and it remains attached in large quantities to plants. It is this accumulation that gives rise to the famous threads of the virgin, particularly visible on warm days at the end of summer and autumn. Some of these filaments are also the work of male spiders, who have set out in search of a mate. The atmospheric electricity, the secret engine of their flight. Most intriguing is that this takeoff sometimes occurs even without the slightest breath of air, on cloudy or rainy days. How to explain this paradox? The answer lies in an invisible but real phenomenon: the atmospheric electric field, a natural electrical circuit that permanently surrounds the surface of the Earth. Researchers from the University of Bristol recreated this field in the laboratory, at levels comparable to those measured in the atmosphere, and observed a spectacular result: when the electric field is activated, the spiders rise into the air; when it is deactivated, they immediately descend. This experiment proves that spiders can take off without any air movement, thanks to this invisible electric force that complements the effects of the wind. Silk, long considered only an electrical insulator, would thus also show the ability to detect these fields. A mechanism reminiscent of that of other insects, such as bumblebees with flowers or domestic bees that use it to communicate in the hive. Atmospheric electricity thus acts as a real push, providing the lift necessary when the wind is absent. A phenomenon that goes far beyond spiders. Ballooning is not limited to spiders. This passive flight, carried by a long thread and by air currents, is also observed in some caterpillars, butterflies, and mites. Sometimes the term aerial plankton is used to describe the entire set of these small creatures that travel in this way through the sky, at the mercy of the ascending currents of sunny summer and autumn days. This dispersion plays an essential role in the dynamics of populations and contributes to ecological resilience, allowing many species to colonize new areas. For hikers, these threads of the virgin remain a subtle but fascinating spectacle: a light haze revealing sometimes a vegetation entirely covered with silk. This phenomenon simply translates the natural rhythm of animal life in autumn. With or without wind, nature always finds a way to move. Between subtle air currents and invisible electricity, these small white threads tell a story much more complex than it seems. Next time you come across one of these filaments attached to the vegetation, perhaps you will look at the sky a little differently.