Common name(s): caddisflies
Small to moderate (1.5mm to 40mm), with long, multi-segmented filiform antennae (which are often longer than the wings), reduced mouthparts (no proboscis) but well-developed maxillary and labial palps.
Caddisflies have large compound eyes and two or three ocelli. The prothorax is smaller than the meso- or metathorax. Tricoptera wings are differentiated from lepidopteran wings by differing venation, and are hairy (or scaly) wings, lacking the discal cell and with fore wing anal veins looped. Hind wings are larger than fore wings. Adults are nocturnal and are attracted to light.
Fun facts: There are over 10,000 species in more than 40 families worldwide. They are holometabolous, with a moth-like adult (as Tricoptera are closely related to the Lepidoptera).
Immature staged (larvae) are aquatic, often bearing the case with makes the order famous, but many are free-living, with three pairs of segmented thoracic legs and lacking abdominal prolegs.
The larvae have five to seven aquatic instars, with fully developed mouthparts and three pairs of thoracic legs, each with at least five segments, and without the ventral prolegs that are characteristic of lepidoptera larvae. The tracheal system in larvae is closed, with tracheal gills often on most if not all abdominal segments. Gas exchange is also cuticular, enhanced by the larvae in its tubular case.
The pupa is aquatic, enclosed in a silken case, with large mandibles to chew its way out of the pupal case (cocoon). It also has free legs with setae to swim to the surface.
Caddiesflies are, for the most part, univoltine. Development can exceed one year in high latitudes and elevations. Larvae are free living, net-spinning, or saddle-purse making or tube-case making. They exhibit diverse feeding habits. Net-spinners are restricted to flowing waters, with case-makers frequent in standing waters. Adults might ingest nectar or water, but often do not feed, and are relatively short-lived.
The name's origin: it has been suggested to derive from cadaz or caddace (caddys), a word of variable spelling used in Shakespearean times to refer to a ribbon made from a certain kind of yarn sold by traveling vendors, who because of this were sometimes called "cadice men". Caddice men would often pin samples of their wares to their clothing, a habit which may have suggested the name caddisfly or caddisworm for the larvae of caddisflies, who exhibit the analogous behaviour of attaching bits of leaves and twigs to the outside of their cases. (from the web site listed below).
Tricoptera and Lepidoptera are sister groups. Together the two orders comprise the monophyletic superorder Amphiesmenoptera, or "dressed-up wings", the name referring to the dense clothing of scales or hairs on the wings.
sourced, in part, by The Insects: An outline of entomology, second ed. Gullan, P.J. and P.S. Cranston. Blackwell Science, Great Britain, 2000.
Parasitic Insects. Askew, R. R. Heinmann Educational Books, London, 1971.