Our intrepid port biologist faces down a cross orb weave spider. Photo credit: Patrick Ammann.
Friday the 13th came early for our trusty intern Patrick and me.
We headed out into the field last Friday to monitor one of the Port’s habitat sites. The sun was shining, birds were singing, we were in good spirits as the weekend was upon us.
Then, as we walked further into the site, it grew darker from the tree cover and the shrubs became denser. As I was forging a path, I felt that dreaded wispy thread on my skin. Blech. I walked right into a spider web.
After I freed my face from the web we looked around and noticed spiders. Lots of spiders. Specifically cross orb weaver spiders. They were EVERYWHERE.
If you are an arachnophobe, don’t worry! We aren’t experiencing an influx of spiders. These spiders are just more visible now because they have grown up over the summer and have reached their mature size (1/4-1 inch not including legs).
Females are larger than males and can be seen this time of year in their round or “orb shaped” webs waiting for males to find them. Females typically build the webs which can be as big as three feet in diameter!
A cross orb weaver spider in its web. Photo credit: Patrick Ammann.
A male will tap on the web to let the female know he is not prey. After mating, she eats him anyway. He died for a good cause, though. He provides the female a calcium rich meal that will go towards producing eggs.
These spiders may look big and scary—granted they do eat each other!—but they are harmless to people and pets. They aren’t aggressive and would rather bounce up and down on their web to confuse potential predators than waste their venom. They trap insects including pests such as mosquitos, wasps and flies in their web. Once the spider feels the vibrations of an insect getting trapped in the web it will move to the insect, inject it with venom to paralyze it before eating it and wrapping it in silk.
If you are lucky enough to have these spiders in your garden, consider keeping them around. They help by killing pests that may transfer fungal and bacterial diseases from plant to plant.