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!


Katherine Maslenikov said...

Yes! I keep finding giant house spiders that my cats have killed and the Cross orbweavers seem to keep making the same giant webs across my walkway every day- right at face level- for me to walk through.

Anonymous said...

I've come across 2 giant house spiders and the orbweavers are all around my house!!!

Unknown said...

I think we're so lucky to have experts like Crawford in our community who are not only knowledgeable, but also willing to help us learn. Thanks!

Tracy Mehlin said...

Tonight I plan to move all the orbweavers that have lived in my house for the summer outside. They've helped keep the fruit flies under control. Last year I let a "spider pet" over winter in a window frame and when her babies hatched in spring I had hundreds of them in my living room. Whoops!

HappyHeartbeatsCounters said...

I don't mind spiders as long as I don't get bit again by a Hobo spider

Anonymous said...

We usually have a couple of the orbweavers at this time of year. This year I counted 6 in the front yard, the same in the back and at least 10 in the side yard. And too many housespiders to count this year.

Anonymous said...

Sometimes you can grab the orbweavers, they don't seem to mind to much, but other times they get angry and show their fangs. Boy when they do that I flick em right out of their web see how they like that! I like spiders. Well the smart ones anyways, like the bold jumping spider. Their curiosity gets them in all kinds of trouble its humor to watch, and unlike the dumb spiders, they will look you right in the eye.

Anonymous said...

For some reason,the giant house spiders are mostly in my bathtubs, where they cannot get out. I take them outside, although I hear they don't survive we'll out there, but at least they have a chance!

Harry Saka said...

I have several Tegenaria wandering around my living room walls at the moment. I note that whenever two 'meet.' head on they are very cautious and back off rapidly when they detect the other is the same size or bigger than them. They disappear for a few day then startle me by showing up again unexpectedly usually running across the floor. The spider myth page says house spiders do not live outside but my coal-shed is full of them. I have seen them on the exterior wall of my house at night and also under stones and in junk in my yard. I even found a large one in the engine compartment of my car They are definitely tegenaria as they have the unmistakable chevron markings.

Joe Rodriguez said...

Thank you for this information. I was just walking around my yard tonight in Central Florida wearing a headlamp because I was cleaning up some stuff and I saw dozens of little reflections everywhere. I was wondering what they were and it turns out they were spiders, Everywhere. I didn't believe all of the reflections were spiders because there were SO many, but after checking about 6 of the reflections, yup they were all spiders. At least this article helped me to identify that they are common Southern House Spiders. I just never knew that so many were crawling around my yard at night!

Anonymous said...

I keep finding black widows/brown widows around the outside of the house. Many other different spiders find their way in the house. I found babies in a picture frame while I was dusting!

Anonymous said...

I've been seeing some Giant House Spiders in my garage (not to be mistaken with a hobo) and one is getting close to 2.5-3 in long (in legspan.) I love to feed them and watch them grow every year! They are super entertaining and pose no threat to humans (even if they were for some reason aggressive [which they aren't], the Giant House Spider isn't venomous enough to make a bite that exceeds what you'd wake up to on a usual morning.) Note: it IS true that Hobo Spiders are more venomous than a GHS, but they aren't aggressive (they just run away; a.k.a. very skiddish) and I've picked up many (with care.) So, PLEASE don't worry about them.

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