Caddisflies: The Underwater Architects - Paperbackby Glenn Wiggins (Author) Caddisflies constitute the insect order Trichoptera in which some 10,000 species are known in the world, including about 1400 in North America. Fossil evidence shows that caddisflies originated in the Triassic period, 200 250 million years ago. They are important links in the movement of energy and nutrients through freshwater ecosystems due largely to the extraordinary diversification in their larval architecture, which