Spiders in Mulch

Asked April 8, 2019, 12:22 PM EDT

I live in Glendale-Glenmont in Baltimore County. I recently had mulch (natural brown) put on a steep hill in my backyard which borders a wooded area. I had planted some ground cover last year (vinca minor) and freshened the mulch to keep weeds down. Last night after sundown when shining a flashlight on the hill I saw dozens (if not hundreds) of shiny reflective specks interspersed throughout the mulch — upon closer inspection I discovered they were EYES staring back at me! from many ground-crawling spiders within the mulch (I am including a pic the best I could do under the circumstances). They look like wolf spiders to me but they are small - about half inch to an inch. Is this number of spiders normally occurring at this time of year? Did they come from the woods or was my mulch infested? I know spiders can help eat other garden pests, but is it harmful to have so many spiders in near proximity to the home (about 25 feet)? I have to say it freaked me out a little. I’m not a gardener or an entomologist, so your expertise is greatly appreciated!

Baltimore County Maryland wildlife groundcovers invasive wolf spider

5 Responses

It looks like you have a wolf spider there. They are harmless to people and beneficial predators of insects in nature. They come out at night to search for food. They are "good guys" in the garden because they help to reduce pest populations. We cannot say if they came in the mulch or from the surrounding area (perhaps both). Here is additional information about them and other beneficial spiders.
https://extension.umd.edu/hgic/topics/predatory-spiders
https://ento.psu.edu/extension/factsheets/wolf-spiders

Occasionally wolf spiders can be found in the home (typically in the fall). Please refer to this article (page 7) for more information and what you can do.
https://extension.umd.edu/sites/extension.umd.edu/files/_docs/programs/ipmnet/17Oct13L.pdf

Christa

Thank you. Glad to hear they are beneficial in the garden. However, are there ever too many spiders in a given area? There are hundreds and I saw babies today too.

The landscaper checked his reserve mulch and it did not have spiders, so they must have been in the hill and/or woods previously.

There are many spiders in nature; they are a normal part of the environment. We do not recommend trying to control them.

Christa

Thank you. So there is no risk of overpopulation then?

No. Spiders themselves have natural predators that will keep their populations in check.

Christa