Winter retreat …
Post mating, the female Wasp Spider, Argiope bruennichi weaves in the region of five flask-shaped egg cocoons, typically containing several hundred eggs, in the higher parts of the vegetation. The eggs overwinter in their cocoons, hatching the following spring.
References:
Roberts, M.J. (1995). Spiders of Britain & Northern Europe. London: HarperCollins.
http://srs.britishspiders.org.uk/portal.php/p/Welcome [Accessed, 9th September 2018].
https://www.buglife.org.uk/bugs-and-habitats/wasp-spider [Accessed, 9th September 2018].