I have a love-hate relationship with spiders. I’m semi-terrified of them, especially when they appear in unwanted places (e.g., the shower), but I find watching them build their webs fascinating, and many, like this marbled orb weaver (Araneus marmoreus) are showy, brightly colored, and beautiful in their own spidery way. In addition to the bright colors and pattern, this marbled orb weaver is also striking because of its size. Her abdomen alone was larger than my thumbnail. Let’s just say, I was happy to notice her on a trail kiosk and not in my house.
Marbled orb weavers, however, are sexually dimorphic, with the females being substantially larger than the males. This size disparity has led to interesting courtship behavior in this species, as well as in other orb weaver species where females tend to be much larger. Because males are considerably smaller, they must be cautious when approaching a female so they are not mistaken for prey. To signal his presence, the male begins by plucking at the edge of the female’s web, and waits for her to respond by tugging at the web in return. Having been thus “invited” in, the male attaches a mating thread to the female’s web, from which she will hang upside down. Once she is in position, the male approaches, tapping on her back a few times before initiating mating (as if to once again convince her he’s not food?), and then retreats from the female’s web quickly after copulation.