The amorphous plug formation in the giant wood spider <i>Nephila pilipes</i>, a highly polygamous and sexually dimorphic species, takes place not during mating, but during oviposition.

<p>A, giant female (left) and small male (right); B, female genital area, intact, arrows indicate paired copulatory openings; C, female genital area covered with a hard amorphous plug (AP); D, two types of plugs in a female, image shows a removed AP with several male embolic leftovers lodged in each copulatory opening; E–G, female spins an egg sac (E) and deposits in it fertilized eggs (F–G); the red AP covering the epigynum (H, arrow), is thus a side product of egg-laying, yet it functions as copulation prevention (see text). Images by M. Kuntner (A, D, H), M. Gregorič (B, C) and S. Zhang (E–G).