To the Lias also can be traced back the Neuroptera, the Trichoptera, the orthorrhaphous Diptera and, according to the determination of certain obscure fossils, also the Hymenoptera (ants).
The Mecaptera, with their predominantly longitudinal wing-nervuration, serve as a link between the Neuroptera and the Trichoptera, their retention of small cerci being an archaic character which stamps them as synthetic in type, but does not necessarily remove them from orders which agree with them in most points of structure but which have lost the cerci.
The standing of the Trichoptera in a position almost ancestral to the Lepidoptera is one of the assured results of recent morphological study, the mobile mandibulate pupa and the imperfectly suctorial maxillae of the Trichoptera reappearing in the lowest families of the Lepidoptera.
Orders: Neuroptera, Coleoptera, Mecaptera, Trichoptera, Lepidoptera, Diptera, Siphonaptera, Hymenoptera.
CADDIS-FLY and Caddis-Worm, the name given to insects with a superficial resemblance to moths, sometimes referred to the Neuroptera, sometimes to a special order, the Trichoptera, in allusion to the hairy clothing of the body and wings.
Apart from this feature the Trichoptera also differ from the typical Neuroptera in the relatively simple, mostly longitudinal neuration of the wings, the absence or obsolescence of the mandibles and the semi-haustellate nature of the rest of the mouth-parts.
More recently the subdivision of the Linnean Neuroptera has been carried still further by the separation of the caddis-flies and scorpion-flies as distinct orders (Trichoptera and Mecaptera respectively), and by the withdrawal of the " Pseudo-neuroptera " from the Orthoptera - with whose typical families they have little in common - and their division into a number of small orders.
At the base of each wing projects a dorsal lobe - the jugumand the neuration is predominantly longitudinal, resembling so closely that of the lower Lepidoptera (q.v.) that a nearer relationship of the Trichoptera to that order than to any group of the old Linnean Neuroptera is certain.
Fossil Trichoptera occur in rocks of Liassic age.
Frequently the whole of the Trichoptera are included in a single family, but most special students of the order recognize seven families.
In all Trichoptera the maxillary palps of the female are fivesegmented.
McLachlan, Trichoptera of the European Fauna (London, 1874-1880), and " British Trichoptera " in Trans.