For the most part, bed bug nymphs look like miniaturized versions of adult bed bugs. They have flat bodies with 2 thin antennae, 6 legs, and a large, oval-shaped abdomen.
The main differences are that they’re smaller in size, lighter in color, and their antennae seem slightly longer in proportion to the rest of their bodies.
After each molt, it increases in length by approximately 0.5 to 1 mm. Baby bed bugs are around 2 mm long in the 2nd instar stage, 2.5 mm long in the 3rd instar stage, 3 mm long in the 4th instar stage, and 4 mm long in the 5th instar stage.
However, bed bug eggs are slightly different. They have a higher resistance against chemicals, heat, and cold which allows them to sometimes survive certain types of bed bug treatments.
If an exterminator sprayed your home for bed bugs, there’s a chance that some eggs may survive and then later hatch into new baby bed bugs. That’s why some people might still see some baby bed bugs even after their home has been treated.