Quote:
Originally Posted by The Lone Ranger
As for the patterns that many orb weavers (notably, spiders in the genus Argiope) weave into their webs, there is some evidence that they are mimicking nectar guides. The fact that these patterns are often made from silk that has a different chemical composition from the silk that makes up the rest of the web -- silk that is often highly reflective of ultraviolet light -- supports this supposition.
What are nectar guides? Many insects can see into the ultraviolet portion of the electromagnetic spectrum, and many flowers have patterns that are visible in ultraviolet light but not visible light. These patterns are thought to help attract the attention of pollinating insects, and guide them to where the pollen (and nectar) is located -- hence the term "nectar guides."
So, in other words, the patterns that you often see in the webs of spiders may be there to lure in pollinating insects. According to some tests, webs with these patterns capture 50% more insects, on average, than do webs which lack these patterns.
A Potentilla flower in visible light (left) and in ultraviolet light, showing the nectar guides. |
I was familiar with the knowledge that flowers reflected patterns in the ultraviolet but I didn't know that spiders used that to lure insects into their web. It would be instructive to be able to see into the ultraviolet to see the different patterns on the flowers.