Can the welts from a bed bug bite still show up after the bed bugs are gone?

Possibly: Your body may still be responding to the bug bites and there can be a delay. If the bites/rash persists and new ones progress, an appointment with your doctor can perhaps give more answers. Good luck.

How much later???: may have no sx's/signs except for 2 small skin puncture points. A reaction may show from 1 hr to several days later. It can cause itchy, pink, swollen, lesions w clear center. If hypersensitive blisters may occur. Telltale sign is linear track of lesions from sequential feedings – doesn't always occur. Bites are in areas exposed while sleeping-arms, shoulders, neck & legs.