courtship. Female Zygiella x-notata store male sperm after mating, subsequently producing one egg sac during late autumn. Females that survive through winter sometimes produce additional egg sacs in the spring with their previous mate's stored sperm. Male choosiness Adult male Zygiella x-notata spiders have been found to be choosy for female mates in high competition environments. Bel-Venner et al. show that under conditions of weak intrasexual competition, males pair opportunistically with females, whereas in highly competitive environments, males selectively guard females according to their own competitive ability. This demonstrated a particular size assortative mating behavior in the differential mating preferences of Z. x-notata males, where large males frequently chose to mate with larger, more fecund females, and smaller males chose to mate with smaller females. Mate guarding Premoult females are a vital resource in the reproductive success of male Zygiella x-notata. Prior to copulation, male spiders try to guard a female before her final moult, when she becomes sexually receptive. By guarding the female, a male expects to be his guarded female's first copulation after becoming sexually receptive. This provides a significant reproductive benefit to the male, as mate guarding tends to lead to reproductive success. Bel-Venner & Venner studied the precopulatory mate guarding behavior of Zygiella x-notata. They found mate guarding to be a widespread phenomenon among their population of interest, and observed strong competition between males to guard females with the frequent action of male takeover. As predicted by sexual selection theory, larger males were found to be more successful at guarding females and evicting smaller males from their guarding positions. Although there is an energetic cost to mate-guarding, males who engage in this behavior incur differential reproductive success on the basis of increased body size and competitive ability. Vibrational courtship The orb webs of female Zygiella x-notata spiders hang vertically under high tension conditions as two-dimensional sheets of silk. Male spiders of this species have been found to utilize the high tension of the web's silk threads to send vibrational courtship signals to the resident female. A study conducted by Tarsitano & Kirchner analyzed the vibratory patterns associated with this courtship ritual. Male Z. x-notata spiders were found to produce three types of vibrational courtship signals on the female's web. A periodic "pulling" signal, a "plucking" signal, and a "burping" signal were identified. The "pulling" and "plucking" signals are both performed by the male immediately prior to