Bombyx mori 300 to about 900 m (1,000 to 3,000 ft) long. The fibers are very fine and lustrous, about 10 μm (0.0004 in) in diameter. About 2,000 to 3,000 cocoons are required to make a pound of silk (0.4 kg). At least 70 million pounds of raw silk are produced each year, requiring nearly 10 billion cocoons. Due to its small size and ease of culture, the silkworm has become a model organism in the study of lepidopteran and arthropod biology. Fundamental findings on pheromones, hormones, brain structures, and physiology have been made with the silkworm. One example of this was
Visceral larva migrans the skin. A list of causative agents of larva migrans syndromes is not agreed upon and varies with the author. Visceral larva migrans Visceral larva migrans (VLM) is a condition in humans caused by the migratory larvae of certain nematodes, humans being a dead-end host, and was first reported in 1952. Nematodes causing such zoonotic infections are "Baylisascaris procyonis", "Toxocara canis", "Toxocara cati", and "Ascaris suum". These nematodes can infect but not mature in humans and after migrating through the intestinal wall, travel with the blood stream to various organs where they cause inflammation and damage. Affected organs can include