The Dangers of Courtship For The Male Garden Spider Araneus diadematus

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It’s amazing what you see sometimes as you travel through your own backyard. I spied this female Araneus diadematus some days ago. She is really quite a big individual and had made a large orbweb stretched between a plant pot and some shrubbery. Here she has a good meal ready to go in the shape of a Hawthorn Shieldbug .. in fact, to my crazy mind, she looks like a band member ready to knock out a tune on it.

The next day, on the late afternoon, I spotted the handsome male Araneus diadematus apparenty repairing and tidying her web for her at a distance. But he had also spun a strong silken quick release safety line … more on that later.

In the above image we can see how large the female is compared to the male. She looks rather intimidating … and she is. I watched as the male Araneus diadematus tentatively approached her along the web, getting a little closer, the female closing the gap … and the male backing off from time to time keeping a little distance between them. He was testing the waters, and so he should. Female Araneus diadematus practices sexual cannibalism before and after insemination. One thing in his favour is the large food package she already has nicely wrapped up … but he certainly didn’t want to be seconds.

Eventually they closed the gap but he was still very sheepish and kept darting back … and on a couple of occasions when he must have read the situation as potentially dangerous rather than amorous he used his pre-made quick release safety line to swing back a good distance out of harms way. They must have been playing this cat and mouse courtship game for a couple of hours … and I don’t know what the outcome was in the end for the male. The next day had seen overnight rain which had damaged some of the web, but the female was found sheltering under a leaf. The male was nowhere to be seen. He was either inside her as last nights late supper … or he had gone off in search of another mate with an extra swagger to his gait.

Sexual cannibalism in spiders is a long-standing evolutionary paradox because it persists despite extreme costs for the victim, usually the male. Several adaptive and nonadaptive hypotheses have been proposed to explain this phenomenon, but empirical studies are still scarce and results are inconclusive.