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The golden princess's secret revealed

Who has never been fascinated by a female Argiope bruennichi, the beautiful and intriguing wasp spider otherwise so common? Who has never wondered why our golden princesses generally decorate their otherwise rather ordinary web with a particular zigzag ?

Argiope bruennichiArgiope bruennichi - (c)Laurence Didion

Multiple explanations have been offered for the use of this silvery “stabilimentum” ( the scientific name of this decoration) :  to scare away birds, attract mates, offer camouflage, provide shade from the sun ... But scientists from the University of Incheon, South Korea, published last September in Behavioural Ecology and Sociobiology, an article bringing evidence of a completely different usefulness. They presented evidence that Argiope bruennichi produces zigzag decorations to... preferably attract a certain type of bigger prey, insect pollinators sensitive to UV light.
This has been demonstrated by comparing the preys caught into decorated and non-decorated webs and the type of prey caught. The number of flies, wasps, beetles, and butterflies – previously shown to be highly attracted to UV light– suggests that the spiders are using this highly reflective pattern to take advantage of this attraction. “ However, the researchers also said their findings do not rule out the possibility that stabilimentum have other purposes, such as mechanically strengthening the web.”, says Dan Cossin, in The Scientist.

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Illustration : Argiope
Sous-titre : "Argiope Bruennichi on its pollen stained web".