2, II), while in moths and caddis-flies they are reduced to mere vestiges or altogether suppressed.
In some midges and in caddis-flies the serosa becomes ruptured and absorbed, while the germ band, still clothed with the amnion, grows around the yolk.
A gnat pupa swims through the water by powerful strokes of its abdomen, while the caddis-fly pupa, in preparation for its final ecdysis, bites its way out of its subaqueous protective case and rises through the water, so that the fly may emerge into the air.
Includes the caddis-flies.
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.
Although caddis-flies are sometimes referred to several families, the differences between the groups are of no great importance.
The larvae known as caddis-worms are aquatic. The mature females lay their eggs in the water, and the newly-hatched larvae provide themselves with cases made of various particles such as grains of sand, pieces of wood or leaves stuck together with silk secreted from the salivary glands of the insect.
The above sketch may be regarded as descriptive of the lifehistory of a great majority of species of caddis-flies.
Caddis-flies are universally distributed.
Comparatively only a few species are, for part of their lives, denizens of fresh water; these, as larvae, are parasitic on the eggs or larvae of other aquatic insects, the little hymenopteron, Polynema natans, one of the " fairy-flies " - swims through the water by strokes of her delicate wings in search of a dragon-fly's egg in which to lay her own egg, while the rare Agriotypus dives after the case of a caddis-worm.
As first used by Linnaeus (1735) it included all insects with mandibulate jaws and two pairs of net-veined wings - dragon-flies, May-flies, stone-flies, lacewing-flies and caddis-flies - and it has been employed in the same wide sense by D.
The other groups of the old Linnean order (such as lacewing-flies and caddis-flies)--which are hatched as larvae markedly unlike the parent, develop wing-rudiments hidden under the larval cuticle, and only show the wings externally in a resting pupal stage, passing thus through a " complete " metamorphosis and falling into the sub-class Endopterygotawere retained in the order Neuroptera, which thus became much restricted in its extent.
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.
And no student can doubt that the stone-flies are akin to Orthoptera and the caddis-flies to the Lepidoptera, while dragon-flies and May-flies stand in an isolated position with regard to all other insects.
The caddis-flies (q.v.) constitute this order, the name of which (suggested by H.
Fleugan, to fly), a designation applied to the winged or perfect state of many insects belonging to various orders, as in butterfly (see Lepidoptera), dragon-fly, may-fly, caddis-fly, &c.; also specially employed by entomologists to mean any species of the two-winged flies, or Diptera.
There are many furrows in the sand where some creature has travelled about and doubled on its tracks; and, for wrecks, it is strewn with the cases of caddis-worms made of minute grains of white quartz.