Strands in orb-weaver spider webs warn birds, attract insects using UV-reflecting silk.


“We are becoming increasingly aware of animal communication outside the range of human sensitivity. Web decorations are silk structures used by orb-web spiders to deceive prey and predators. However, despite the level of interest in these structures, their visibility to prey and predators has never, to our knowledge, been objectively assessed. Here, we use spectrophotometric analyses to show that the decorations of all five tested spider species are visible to honey bees and birds over short and long distances.” (Bruce et al. 2005:299)

Journal article
Spider signals: are web decorations visible to birds and bees?Biology LettersOctober 27, 2016
Matthew J. Bruce, Astrid M. Heiling, Marie E. Herberstein

“Web decorations reflect light in the UV range and may exploit an inherent sensory bias of insects toward UV light, thereby increasing the foraging success of the spider. Decorations may also deter visually hunting predators such as birds and wasps by hiding the spider or by advertising the web’s noxious characteristics. Finally, decorations may advertise the position of the web to larger animals such as birds, which then avoid contacting and accidentally damaging the web.” (Herberstein and Fleitsch 2003:623)

Journal article
Effect of abiotic factors on the foraging strategy of the orb-web spider Argiope keyserlingi (Araneae: Araneidae)Austral EcologyOctober 27, 2016
M. E. Herberstein, A. F. Fleisch

“The conspicuous white silken adornments known as stabilimenta, which are commonly found in the orb web of some spiders, appear to be protective devices that warn birds of the presence of webs in their flight path. Webs endowed with artificial equivalents of stabilimenta tended to survive intact the early morning period when birds are on the wing; unmarked webs showed a high incidence of destruction.” (Eisner and Nowicki 1983:185)

Journal article
Spider Web Protection Through Visual Advertisement: Role of the StabilimentumScienceMay 10, 2006

St Andrew's Cross SpiderArgiope keyserlingiSpecies