MSU Extension

Michigan State University Extension offices across Michigan are frequently asked to help with the identification of spiders. I have personally assisted hundreds of clients with spider identification and information about spider bites or the control of spiders in my 21 years in the Grand Traverse MSU Extension office. In recent years, the World Wide Web has become a vast resource of information on spiders that is immediately accessible to anyone, so one might think that my services are not needed as much as they used to be. However, the sources of information on the web have only served to confuse many people or cause them to make erroneous identification of spiders. While a thorough examination of this situation is not possible in a short article, I’ll try to explain a few of the reasons for the difficulty of spider identification and understanding their importance.

Even though spiders are very common creatures (over 3,700 species in North America) there are really not very many good references for spider identification. Even the best reference for our area, Spiders of the North Woods, by Larry Weber (Kollath-Stensaas Publishing Co.) only covers a small number of the many species that inhabit our region. I have extensive training and experience in the identification of insects, but I find spider identification to be much more difficult than insects because many of the body parts of spiders are softer than the corresponding insect features, which makes them harder to examine, measure, and even find, especially on the somewhat scrambled specimens that are brought to me after they have been swatted by clients. By comparison, I have been able to identify some insect specimens that have been absolutely flattened by postal canceling machines after they have been mailed to me in a simple envelope.

When untrained people try to identify spiders by “picture-booking” from printed references or images on the web, they are often confronted by several problems. Spider colors can vary quite a bit within a species. Spider maturity is difficult to determine, making it hard to tell if a specimen is a full-grown small species or an immature of a large species. Only a small fraction of the possible species is presented in any one reference. When searching the web, many of the websites that are “popular,” or coming up first on searches, do a very poor job of indicating the geographic ranges of the spiders, leading to many misidentifications.

Just before writing this article, I entered “spider identification” in a Google search. In the top ten suggested websites, there were none that provided adequate information or images to identify most of our Grand Traverse region spiders; some contained outright errors in the labeling of pictures and many contained incomplete or dubious information on the ranges of the spiders that they do cover. This is a very common fault of web references on spiders and insects. Numerous people have contacted me in a panic over a very dangerous spider they are sure they have in their home based on their internet research. Once I get a chance to see the creature in person, these almost always turn out to be a local species that have a strong resemblance to the nasty relative. I must say “almost” because once in a while something interesting does show up – a brown widow, native to southern California, was found in some produce at a local store a few years ago.

I was pleased to find one website, Spiders.us, that has a very sensible approach to the problem of diagnosing spider bites, which is even more difficult than identifying spiders. Numerous things can cause symptoms similar to spider bites, and to make it even more challenging, individuals can react differently to the bite of a particular spider. Each year, many people in northern Michigan seek medical attention for what they believe to be brown recluse bites because of the nature of the symptoms. The brown recluse spider is mainly a south-central United States spider, with a few cases of it being found in far southeast Michigan. Something else, perhaps not even a spider at all, is causing the recluse-like symptoms in our northern areas. The website provides an extensive list of bites and conditions that can produce symptoms that are easily confused with the bites of the brown recluse. If you or anybody you know has experienced the typical symptoms of a recluse bite, it could be very important to check out the information at this site.