Trichoptera - The Caddisflies
Caddisflies are complex insects that few people have heard of. Perhaps one of the most interesting of the insects, caddisflies are considered the ancestors of all moths and butterflies. Fossil records go back to the Triassic period (225-190 million years ago) and some primitive moths retain features similar to those found in modern caddisflies. Caddisflies are found all over the world (except Antarctica) and are associated with well-oxygenated fresh-water ecosystems. They have an aquatic larval stage, which frequently make "cases" that act as portable homes. Fashioned from the detritus of the stream and pond bottoms where they generally live, these cases can be made from sand, tiny pebbles, or bits of wood, even empty snail shells! The idea is to build a home that mimics the substrate, allowing them to feed undetected. Larva can be carnivorous, with some using silk to spin nets with which they catch tiny aquatic organisms. The majority, however, are herbivores or omnivores. They will live as larva for about a year, pupating within a modified form of their larval retreat. Adults are most vulnerable to fish predation upon emergence as they swim or crawl to land. The adults are winged and can live for a month or two, sometimes much more or less. They have an interesting array of mouthparts which they use to consume herbivorous liquids. The ordinal name "Trichoptera" is derived from the Greek words for "hair wing" because of the hairy forewings of the adult. It is these hairs which were, perhaps, modified into the scales which cover the wings of Lepidopterans. Another interesting (and quite mind-blowing) fact is the existence of a species of caddisfly (Philanisus plebeius) whose larvae are found only in tide pools in New Zealand and southeastern Australia. Although the larvae cannot survive long in 100% seawater, the females deposit their eggs inside the coelomic cavity of starfish - the larvae later migrate to tide pools after they hatch! There are about 7,000 described species of caddisflies.
