What do baby bed bugs look like?

Most people picture a bed bug as the adult: flat, oval, rusty brown and about the size of an apple seed. The young ones are easy to miss, and they are often the first thing people find. A tiny pale speck crawling on a pillowcase, or a smear of red on the sheet after squashing something that looked like a crumb, is frequently a nymph.

Knowing what the young look like matters for two reasons. It tells you that bed bugs are breeding in the room, not just passing through on a bag. And it explains why most treatments need more than one visit.

The five stages

A bed bug hatches from an egg about 1mm long, pearly white and slightly curved, usually glued into a seam, a crack in a bed frame or the edge of a carpet. What comes out is a nymph, a smaller version of the adult with no wings, six legs and a beak folded under its head.

Nymphs moult five times before they become adults, and each moult needs a blood meal first. Roughly:

• First stage: about 1 to 1.5mm, pale yellow or nearly clear. Before feeding it is very hard to see against white bedding; after feeding it shows as a bright red dot.
• Second and third stages: about 2 to 3mm, straw to light brown, still slightly translucent at the edges.
• Fourth and fifth stages: about 3 to 4.5mm, mid-brown, looking very like a small adult.
• Adult: around 5mm, mahogany brown, flatter and broader. The NHS describes adults as up to 5mm long.

At each moult the nymph leaves its old skin behind. These pale, empty, bug-shaped shells collect in mattress seams and along the edge of the bed base, and they are one of the clearest signs that bed bugs are living there rather than visiting.

Why they look red sometimes

A nymph’s body is thin enough to show what is inside it. Straight after feeding it swells and turns bright red with blood; over the next day or two it fades to a darker red-brown as the meal is digested. A nymph that looks red and plump has fed in the last few hours, which usually means someone has been bitten in that bed recently.

How fast they grow

Development speed depends on temperature and on how easily they can feed. The University of Kentucky’s entomology guidance puts egg to adult at about five weeks in warm conditions, with eggs hatching in about six to ten days. In a cooler room, or one where nobody has slept for a while, it takes much longer.

That timing is the reason a spray course is spread over two or three visits. Most insecticides do not kill eggs reliably, so eggs laid just before the first visit hatch over the next week or two. The second visit is timed to catch those nymphs before they are old enough to lay eggs themselves. Heat treatment is different: held at the right temperature, it kills eggs and nymphs in the same day, which is why it is one visit and a check.

Baby bed bugs or something else?

Plenty of small pale insects turn up in bedrooms, and not all of them bite. A few points help tell them apart:

• Shape: bed bug nymphs are flat and oval, wider at the back, with no wings. Booklice are much smaller and softer, and run quickly. Carpet beetle larvae are hairy and stripy, more like a tiny caterpillar.
• Where you find them: nymphs stay close to where someone sleeps or sits for long periods, in seams, joints and the underside of the bed base. They do not usually wander across open floor in daylight.
• What is around them: look for the dark spotting of droppings, shed skins and eggs in the same place. The NHS lists these, together with bites and blood spots on sheets, as the common signs.

If you are not sure, catch one on clear sticky tape or in a sealed bag, or take a sharp photo next to a coin. A specialist can usually confirm it at a glance, and it saves an inspection hunting for evidence.

What finding them means

Nymphs mean there is at least one adult female in the room and that she has been laying eggs. It does not necessarily mean the whole home is affected. In many cases the bugs are still confined to one bed or one sofa, which is the cheapest point to deal with them.

What makes things worse is moving. Sleeping on the sofa or in another room to escape the bites gives the bugs a reason to follow you, and they spread. Shop sprays and foggers tend to do the same thing, driving bugs out of the treated spot and into neighbouring rooms, or into the flat next door in a converted house. Keep sleeping in your own bed until it has been treated.

While you arrange treatment, the NHS advises washing affected bedding and clothes on a hot wash at 60°C and tumble drying them on hot for at least 30 minutes, and vacuuming the room. Bag washed items so they stay clean.

Getting rid of them

Because nymphs hide in the same places as adults, a professional treatment deals with both. A specialist will inspect the bed, the furniture near it and the rest of the rooms, then recommend a spray course with steam or a heat treatment depending on how far it has spread. Our guide to inspections in Bristol explains what is checked, and the Bristol price list shows typical costs.

If you have found baby bed bugs in a Bristol flat or house, you can book a visit through Bristol bed bug treatment, and a local specialist will confirm what you have and give you a fixed price.