Sighting in Montady, October 23, 2015

At around 1:50 p.m., a couple noticed an unusual phenomenon in the sky that intrigued them: three round balls from which bursts of threads several tens of metres long streamed out. Thousands of small creatures came out of the balls, whirling around and looking as if lit by diodes. One of the two took photographs. Only one witness account was collected.

The investigation found that the white threads in the photos had all the characteristics of spider silk, known as "gossamer" or "angel hair" ("fils de la Vierge"). Tiny young spiders use these threads to be carried off by the wind, a phenomenon called ballooning. October is a very good time for it, and it also needs fine, dry weather and a light breeze, which were the conditions that day according to the weather record. These very fine threads are only visible when laden with moisture or seen against the light. It is normal for them to vanish as one approaches, since the observer's angle to the sun changes or the threads dry quickly. The balls could have been clusters of spiders.

The GEIPAN classed the case as B: probable observation of migrating young spiders and their silk threads.