The short answer
Bed bugs, also called 木蝨 in Hong Kong, are small, wingless, blood-feeding insects — adults run 5 to 7mm, flat and reddish-brown before feeding, swelling and darkening to a deep red after a blood meal. They can't fly or jump, only crawl.
During the day they hide in narrow gaps close to where you sleep — the seam along a mattress edge, bed frame joints, sofa cushion gaps — and come out to feed at night. Both the common and tropical bed bug are found in Hong Kong.
Check for insects and other signs in those gaps; bites alone cannot confirm bed bugs.
- Scientific name
- Cimex lectularius / Cimex hemipterus
- Chinese name
- 床蝨
- English name
- Bed bug
How to identify a bed bug
- Size: adults are about 5 to 7mm, flat and oval — visible to the naked eye, no magnifying glass needed.
- Colour: flat and reddish-brown before feeding; swollen and deep red after a blood meal, moving more slowly once fed.
- Can't fly and can't jump — only crawls, which is why every infestation arrives by hitchhiking (luggage, furniture, clothing) or spreading in from a neighbouring flat.
- Nymphs are tiny (around 1mm) and near-translucent, very hard to spot before they've fed.
Where do bed bugs hide in a Hong Kong home?
Bed bugs stick to narrow, dark gaps close to where you sleep and rarely come out during the day:
- The seam along a mattress edge, and the gap between mattress and frame
- Bed frame joints and behind the headboard
- Sofa cushion seams and armrest gaps
- Carpet edges near the bed, behind wall sockets (in more advanced cases)
- Checking tip: look for tiny black spotting and reddish-brown smears — these often show up before you spot a live bug
Why does it matter?
Reactions to bed bug bites vary: some people develop itchy swellings, while others have no visible reaction. Discomfort can disturb sleep. Bed bugs are not currently known to spread disease. Bites do not identify the insect; seek medical advice if symptoms persist or worsen.
Does spraying insecticide yourself work?
Spraying visible insects can miss bed bugs and eggs in narrow gaps. Inspect hiding places first, then select treatment for the materials and conditions found. Follow pesticide labels rather than increasing the dose. For entry routes, see our how bed bugs spread guide; for telling bites apart, see our bite comparison guide.
How to keep them from coming back
CHP: bed bug signs and travel-prevention advice
- Inspect every seam of second-hand furniture, especially sofas and bed frames, before bringing it in
- After a trip, keep luggage off the bed and hot-wash or steam-treat your clothing
- If a nearby flat has a known case, check your own home early
- Check early if you spot bites or black spotting — don't wait for a full row of bites before acting