INSECT ATTRACTION TO ULTRAVIOLET-REFLECTING SPIDER WEBS AND WEB DECORATIONS

Primitive spiders produce silks that reflect ultraviolet (UV) light and primitive aerial web weavers spin UV-reflecting catching silks that attract Drosophila. Derived, web-spinning spiders in the genus Argiope, however, produce catching silks that exhibit low reflectivity in the UV and, in fact, reflect little light at all. Nevertheless, Argiope decorate their webs with bright, UV-reflecting bars and crosses that attract prey. More insects were intercepted per hour by decorated webs with spiders than by undecorated webs from which the spider had been removed. UV-reflecting decorative silks, together with the UV-reflecting body surfaces of A. argentata, thus apparently act as a visual display that attracts prey. -from Authors