Enterobius vermicularis (Oxyuris vermicularis; pinworm) is a small, white, thread-like nematode that resides in the small intestine. The males are 2.5 mm long with coiled tails and the females measure about 10 mm in length. The females migrate to the perinanal region at night and lay about 10,000 to 15,000 eggs and die causing intense nocturnal pruritus. The infestation is acquired by ingesting embryonated eggs which hatch in the duodenum and migrate to the ileocecal region where they mature. This specimen photo shows several translucent white worms in the lumen of the appendix in a 6 y/o female who presented with acute appendicitis. Image copyright: pathorama.ch.