Bed bug or varied carpet beetle?
These two get mixed up often. The bed bug is rated Be careful and the varied carpet beetle is rated Harmless, so it is worth a closer look.
Why people mix them up
Both are tiny, both turn up in bedrooms and on beds, and carpet beetle larvae can cause itchy red bumps that people mistake for bed bug bites. Finding a small round bug on the sheets after waking up with marks is a common reason for panic.
A bed bug is flat, oval, reddish brown and about the size of an apple seed, with no wings. An adult varied carpet beetle is rounder, smaller and patterned in white, brown and yellow scales like a tiny calico ladybug. Carpet beetle larvae are fuzzy brown grubs. Bed bugs leave dark spots on mattress seams; carpet beetles leave shed fuzzy skins.
Bed bug
Photo: Katja Schulz, CC BY 4.0, via iNaturalist
Size: Adults about 5–7 mm (3/16 to 1/4 inch), about the size of an apple seed; young bed bugs about 1.5–4.5 mm.
- Flat, oval, wingless reddish-brown body when unfed
- Swollen, longer and redder right after feeding
- Six legs and short antennae
- Young bed bugs are pale, see-through or yellowish and hard to see until fed
- Signs nearby: dark rust-colored spots on sheets or mattress seams, shed skins, tiny white eggs, and a sweet, musty smell
Bed bugs bite and can cause itchy welts and lost sleep, but they are not known to spread disease.
Varied carpet beetle
Photo: glmory, CC0, via iNaturalist
Size: adults 2–3 mm (about 1/10 to 1/8 inch); larvae up to about 6 mm (1/4 inch)
- Tiny, nearly round beetle, smaller than a ladybug
- Mottled, calico-like pattern of white, brown, yellow-orange and black scales
- Adults often found on window sills, especially in spring
- Larva is a short, fat, hairy brown grub, wider at the back end, with bands of bristly hairs
- Light brown shed larval skins in closets, drawers or along carpet edges
Varied carpet beetles do not bite, but their larvae chew holes in wool and other natural fabrics, and their tiny hairs can make some people itch.
How to tell them apart
- Carpet beetles are round, hard-shelled and often spotted or patterned, and do not feed on blood.
- Bed bugs are flat, wingless, reddish-brown and found in bedding seams, while adult carpet beetles are round, patterned and found at windows.
Still not sure? Use the picker, and if a bite worries you, call Poison Help at 1-800-222-1222.