Several dozen types of spiders are common in North Dakota. None of them are found exclusively there, but most are of a specifically northern American or European extraction, adapted to changing seasons and temperatures. Data on spider populations are always limited and more or less speculative. Most of the spiders in North Dakota are harmless.

Funnell weaver grass spiders are normally brown or gray and live in tall grasses. They build well-hidden webs in grasses or shrubs. They are only rarely found indoors. Their bite is harmless and not generally painful.

Pirate spiders are the most interesting species of spider found commonly in the state. They are cannibals, living only on other spiders. They are normally darker yellow or brown, and are occasionally mistaken for the dangerous brown recluse spider. The pirate spider spins no web, but uses trickery to eat other spiders. The pirate spider will approach a spider web, tap on the strands to imitate a bug trapped in the web, and then ambush the spider when it comes to see its “prey.”

Orbweb spiders are generally harmless. They are shy, non-aggressive and their bite is without poison. Their webs are large and are created in a circle. Their webs are those that the layman identifies with spider webs in general: round, ornate and more dense as they get to the center. The common zig-zag markings in the center of the web are done by most types of orbweavers. Most are black with some yellow markings. They rarely bite.

The crab spiders are found nearly everywhere. These spiders are tiny, look vaguely like a crab, but get their name because they walk sideways. It does not build a web, but ambushes its prey. It can change color to match its surroundings.

This spider spins a horizontal web that only reaches about 20 centimeters in diameter, often in sunlight, with a hole in the center (unlike the Orbweb spiders, that have a dense center). It has a silver abdomen, which is how species gets its name. It has very thin legs and often lives near lakes or streams. It is generally yellow or white. It is harmless.