The flea's knees (and every other part of its anatomy): Stunning close-ups of see-through water insects . By DANIEL MILLER . Published: 09:57 EDT, 4 May 2013 | Updated: 11:52 EDT, 4 May 2013 ...

Fleas thrive in warm, moist environments. An adult female flea lives an average of 30 to 90 days and can lay 50 eggs each day. Fleas thrive in warm, moist environments.