One possible clue is finding tiny reddish or rusty-colored stains on sheets, pillowcases, or mattresses.

These marks can occur when a bed bug is accidentally crushed after feeding.

They can also come from small amounts of blood associated with feeding.

However, blood spots have many possible explanations, so they aren't definitive proof of bed bugs.

Still, several unexplained stains appearing alongside other signs should prompt a closer inspection.

7. Dark Spots May Appear Around the Mattress

Another potential sign is small dark fecal spots around areas where bed bugs hide.

Inspect areas such as:

A flashlight can make these areas easier to inspect.

Don't forget that bed bugs are very good at hiding. Simply looking at the middle of the mattress may reveal nothing.

8. Bed Bugs Can Hide in More Places Than the Mattress

Many people assume that bed bugs live exclusively inside mattresses.

That's not true.

They can hide in numerous protected locations, including:

Bed frames

Headboards

Furniture joints

Cracks in walls

Behind loose wallpaper

Around electrical outlets

Under carpets

Inside upholstered furniture

As an infestation becomes more established, bed bugs may spread farther from the original sleeping area.