September 19, 2013

Spider Myth: "Why are there more spiders in late summer?"

Every August and September, people ask spider researchers, "why are there so many more spiders this year than usual?" This time of year is when people notice spiders more frequently, but that doesn't mean the overall number or variety of species increases. In fact, there are relatively few native species of spiders around in August and September because it is the driest season.

Here in the Seattle area, a few large non-native spider species, including the cross orbweaver and giant house spider, make themselves more noticeable in late summer.

While orbweavers are more than 100 times as abundant in May just after they hatch, their webs are tiny and not noticeable at that point. By late summer, orbweavers are mature and building much larger webs that put them more conspicuously out in the open.

Cross orbweaver, Araneus diadematus
Photo by Bob Thomson
This is also the time of year when male giant house spiders are sexually mature and wander around searching for mates, so that's why you may spot them more often in late summer than any other time of the year.
Male giant house spider, Tegenaria gigantea

So, there aren't more spiders, rather a few species that are more noticeable.

Have you noticed the cross orbweaver, giant house spider, or other species these past several weeks? Leave us a comment and make sure to explore more myths, misconceptions, and superstitions about spiders on our website.

Posted by Rod Crawford and Cathy Britt

Join the Burke for Bug Blast on Sunday, September 21, 2014 to examine bugs of all kinds from the Burke's collections, learn about the beneficial bugs hidden in your garden with Ciscoe Morris, and more!