5 facts about spider beetles

Updated on: October 20, 2026

Quick overview

• Spider beetles are small, rounded beetles often mistaken for spiders or bed bugs.
• They commonly infest stored foods, including flour, grains, spices, nuts, and dried fruit.
• Spider beetles are not blood-feeding pests and are very unlikely to bite people.
• Infestations can cause costly product contamination in food businesses, warehouses, and commercial kitchens.
• Their tiny size allows them to shelter in packaging, floorboards, walls, and other hidden spaces.
   

Spider beetles turn up in pantries, warehouses, and food prep areas across North America, especially in the northeast. They're easy to mistake for actual spiders, or confuse with bed bugs when they show up somewhere unexpected. For most homeowners, they're a minor nuisance. For food businesses, an infestation can spoil stock fast and cost real money.

Here are five facts to help you spot spider beetles, understand what draws them in, and know what to do next.

1. Spider beetles are tiny insects that look like spiders

The tiny spider beetle earns its name honestly: round body, smooth, shiny shell, and long antennae near the head that pass for extra legs at a glance. Look closer, though, and you'll count six legs, not eight. That's because spider beetles are true beetles, part of the Anobiidae family.

The most common North American species is the American spider beetle (Mezium americanum), at just 1.5 to 3.5 millimeters long. Its reddish-brown, rounded shape is also why it's sometimes mistaken for a bed bug at a glance. Not sure which you're looking at? Our guide to bed bug identification can help, or you can just ask us.

You may also come across the smooth spider beetle or whitemarked spider beetle. Some appear as a glossy black spider beetle, while others are reddish-brown or mottled.

2. Spider beetles are foragers and eat a variety of foodstuffs

Spider beetles tend to come out and feed at night and are usually most active then. They are not very picky about what they eat, either, and have been found nesting and breeding in a wide variety of foodstuffs and materials including:

• Almonds, beans, and wheat
• Flour, rye bread, and cereals
• Paprika and ginger
• Dried mushrooms
• Figs
• Cacao
• Wool, silk, and animal skins
• Books

Given damp conditions and a steady food supply, numbers can climb quickly in commercial kitchens, retail stockrooms, and hospital or hotel kitchens. If you run a food processing or foodservice operation, that's worth taking seriously.

3. Spider beetles are very unlikely to bite you

They're after dry goods and fabric, not blood, and they don't have the biting mouthparts that come with true blood-feeding pests. But this doesn’t mean spider beetles aren’t dangerous: the cost to businesses can be vast, depending on the severity of the infestation.

4. Spider beetles often look for food indoors

Like most household invaders, spider beetles are chasing food, usually hitching a ride in packaged goods or grains rather than sneaking in through a gap in the wall.

Once indoors, the pantry is the obvious suspect, but not the only one. Finding a spider beetle in a bed or bathroom isn't unusual either, since bedrooms and bathrooms can both offer the damp, dim corners these beetles like. Our pantry pest guide covers the usual cupboard culprits, if you'd like a second opinion on what you're seeing.

5. Spider beetles can hide in almost any crack or crevice

Small size means big hiding options: floorboard gaps, skirting boards, chewed-through packaging, attic corners. That's the tricky part. You might spot a spider beetle in a pantry item, while the actual nest sits somewhere else entirely, like an old rodent nest inside a wall. Tossing the bag of flour won't fix that.

How to get rid of spider beetles with Ehrlich Pest Control

Trying to work out what a spider beetle looks like up close, and whether that's really what's on your counter, isn't always easy. Our expert technicians know how to tell a spider beetle apart from a bed bug or other look-alike, and how to trace an infestation back to its real source, whether that's a forgotten bag of flour or a hidden rodent nest.

We'll help you figure out what's drawing spider beetles in, then build a plan to remove them and cut the odds of a repeat visit. Get in touch with your local Ehrlich Pest Control office to book an inspection, whether you need pest control for your business or your home.