There are multiple reasons why this occurs. First, adult male Zygiella x-notata do not produce orb webs and thus reside on window frames or other human structures. This leaves males at a disadvantage, as they can be more easily identified by wasps. Second, the dorsal side of the male, as well as the male's legs and cephalothorax, appear significantly darker than that of the female. When placed in contrast with their residence on human settlements, the dark color of the male is easily visible and thus preferentially located by wasps. Third, male spiders engage in mate guarding behaviors. While guarding their potential female mates, males are typically located on the female's web, outside of her retreat. Here, the male is vulnerable to predation due to his increased visibility. Predation avoidance Due to the significant threat of predation by wasps, Zygiella x-notata has developed defensive behaviors to avoid predation threats. One tactic used by Zygiella x-notata to escape predation by wasps is jumping from webs or off human constructions. In males particularly, this survival behavior consists of jumping down the frame of a window, where he can no longer be located by the wasp. In female spiders, predation avoidance involves a tactic known as "web cleaning". Females' web cleaning behavior involves throwing prey remains out of the web after eating. If either prey or an inanimate object remain stuck on the web, the females will remove the section of web containing the prey or object, and rebuild the section of web. This behavior decreases the predation risk to females by lowering the wasp's visibility threshold. Additionally, web cleaning behaviors often occur at night to reduce the risk of potential predation. During the day, the female remains in her retreat to reduce visibility to wasps, thereby reducing predation risk. Consequences of predation Consequences of predation by wasps include decreased reproductive success of an individual Zygiella x-notata as a result of capture by the wasp, displacement of the spider upon jumping from the web or other structures, and prey theft by the wasp. These all pose physiological and energetic costs to the spider, occasionally resulting in physical impairment or death. Invasive species Zygiella x-notata is considered an invasive species in California, however they are not harmful to humans and they are not known to bite either. The only obstruction they seem to cause is disrupting garden work with their large webs. See also