Monday, December 19, 2016

St. Andrews Cross Spider

I have mentioned numerous times that I have never used insecticides in the vineyard which has enabled the build up of a great number of predators who feast on the bad guys who could do damage.
One of these is the St Andrews Cross spider.
She (the male is a lot smaller and duller) is a colorful lady who spins a quite distinctive web.
The web catches numerous flying insects particularly the grapevine and hawk vine moths who are intent in laying their eggs on the leaves and stems.
When hatched, the caterpillars of these two moths can cause problems.
The spider normally hangs upside down in the web with two paired legs placed along each arm of the cross. The silken cross may be used for strengthening the web, for camouflage or for enhancing prey catches. It has been shown that the cross reflects ultra-violet light which is particularly attractive to insects.
Walking into a web is a bit uncomfortable as they are quite strong and sticky but the bite of this spider is considered harmless or at most to cause a weak local reaction. I don't think I have ever been bitten by one of these despite finding the occasional one crawling on me after a session spraying or green pruning.

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