MONTADY (34) 23.10.2015

On 23 October 2015 at about 13:50, a couple saw an intriguing phenomenon pass through the sky: 3 round balls shedding sprays of threads tens of metres long. Thousands of tiny creatures emerged from the balls and whirled around, looking as though LEDs illuminated them. A witness took photographs. Only 1 account was collected. GEIPAN finds that the photographed white threads have all the characteristics of spider silk known in French as ‘fils de la Vierge’, or ‘angel hair’. Tiny young spiders use these threads to travel with the wind, a phenomenon called ballooning. October is well suited to this observation. Fine dry weather and a light breeze are also needed, and prevailed that day (see the weather record). GEIPAN explains that the extremely fine threads are visible only when carrying moisture and/or backlit. They can disappear from view on approach because the observer’s angle to the Sun changes or because they dry rapidly. The supplied photographs fit the phenomenon. The balls could be clusters of spiders (see photograph). GEIPAN classifies the case B: probable observation of dispersing young spiders and their silk, commonly called ‘fils de la Vierge’.