Stage 3 is divided into two substages, the first of which being 2–3 days after penetration is complete. In 3a, maximum hypertrophy is achieved and the flea's midsection swells to the size of a pea. Due to the expanding flea, the outer layer of the skin is stretched thin, resulting in the appearance of a white halo around the black dot (rear end of the flea) at the center of the lesion. In 3b, the chitin exoskeleton of tergites 2 and 3 increase in thickness and gives the structure the look of a mini caldera. Egg release is common in substage 3b, as are fecal coils. The eggs tend to stick to the skin.