How to Identify a Spider by Region

How to Identify a Spider by RegionWhile the vast majority of spiders are harmless and retiring, their appearance and predatory habits---not to mention their ubiquity in homes and gardens---generate major curiosity, and sometimes outright terror, on the part of humans. While there are tens of thousands of spider species, and exact identification must often be left to seasoned experts, there are a few characteristics to look for---and then to cross-reference with your geographic location.


Difficulty: Moderate

How to:

Things You’ll Need:
  • Taxonomic key
  • Spider field guide
  • Magnifying glass and/or microscope
Step 1
First and foremost, look at the spider's body shape, which should be roughly determinable even from a distance or without magnification. Spiders come in a plethora of shapes and sizes, from minuscule black widows with bulbous abdomens to large and robust tarantulas.
Step 2
Check out the legs, another obvious spider feature. While all have eight, the shape and length vary. Many web-building spiders have disproportionately long and slender legs for feeling a wide swath of strands. Jumping spiders, by contrast, have short, stocky legs, often clustered close about their similarly stout frames.
Step 3
If you're close enough, or have a dead spider under a magnifying glass or microscope, look at the number and orientation of its eyes. These characteristics vary among spider families and can be useful for narrowing the field.
Step 4
Take note of the spider's location and activity. Some build webs and spend much of their time poised upon them, waiting to dispatch entrapped prey. Others, like wolf spiders, are active hunters, scuttling about at good speed.
Step 5
With the above observations, navigate the taxonomic key (often organized in a step-by-step manner); or, less comprehensively, scan your field guide, which may not land you an exact species but could point you to a family or related type. These reference materials also generally contain information about species' geographic ranges---but keep in mind that you may encounter a spider well outside its typical area (because of human transports, intentional and otherwise).
Step 6
If you can secure the spider, or if it is dead, take it in to a county extension office. These offices often provide identification services by entomologists and other experts.

Tips & Warnings

Don't provoke any spider. That's a good way to get bitten---and many species possess venom, even it's only rarely of a sufficient potency and quantity to pose real danger to people.

Article Written By Ethan Schowalter-Hay

Ethan Schowalter-Hay is a writer and naturalist living in Oregon. He has written for the "Observer," the Bureau of Land Management and various online publishers. He holds a Bachelor of Science in wildlife ecology and a graduate certificate in geographic information systems from the University of Wisconsin.

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