"Fore-wings with an oblique membranous dorsal process (jugum) near base,
forming with the dorsal margin a notch or sinus, which receives the costa
of the hind-wings. Hind-wings without frenulum, 1_c_ present, with 11 or
more veins, neuration essentially, almost or quite identical with that of
fore-wings. Fore-wings and hind-wings more than usually remote at origin.
"In the two families, which constitute this highly interesting group, is
fortunately preserved a type of _Lepidoptera_ whose existence could never
have been inferred from a study of other forms. Without a knowledge of
these two families the true origin of the order could never have been more
than a matter of more or less probable conjecture. The _Micropterygidæ_ are
the primeval ancestors of all the Lepidoptera, indicating their origin from
the _Trichoptera_ so nearly that one or two more discoveries might make it
hard to draw any line of demarcation. The _Hepialidæ_ are an offshoot from
the _Micropterygidæ_ (with considerable extinction of intermediate forms),
constituting a separate line of development quite unconnected with any
other _Lepidoptera_; if, as is possible, this separate stem may have ever
given rise to other branches forming distinct families, all trace of their
existence seems to have been lost.
"Imago with fore-wings and hind-wings more or less semi-oval, termen and
dorsum forming a nearly uniform curve.
"Larva with few hairs, with 10 to 16 prolegs, or apodal, living concealed.
"Pupa in _Hepialidæ_ with segments 7 to 11 and in male 12, in
_Micropterygidæ_ with all segments free."--(Meyrick.)
In this work the _Hepialidæ_ alone are dealt with, the _Micropterygidæ_
being reserved {128}for a future work. It may, however, again be mentioned
that the last-named family contains amongst its New Zealand representatives
_Palæomicra chalcophanes_, a species which more closely approximates in
structure to a Neuropterous insect than does any other member of the
_Lepidoptera_. This insect is consequently regarded by Mr. Meyrick as the
most ancient species of the order yet known. The survival of _Palæomicra_
in New Zealand is quite in accord with the existence of such forms as
_Apteryx_ and _Dinornis_ amongst the birds, the tuatara lizard
(_Sphenodon_) amongst reptiles, and _Peripatus_ amongst _Myriapoda_,
archaic forms which have been preserved in this country through its long
isolation from continental areas, and the resulting absence of more recent
competing forms.
Family 1.--HEPIALIDÆ.
"Head rough. Ocelli absent. Tongue obsolete. Maxillary palpi obsolete.
Tibiæ without spurs. Fore-wings with all main veins and costa connected
by bars near base, 1_b_ furcate, forked parting vein strong." (Plate I.,
figs. 22, 23, 24, 28, 29.)
"By no means an extensive family, yet of universal distribution. It stands
more conspicuously isolated than any other group of _Lepidoptera_, for
although it is without doubt a terminal development from the
_Micropterygidæ_ (that is one from which no existing family has
originated), the gap between them is considerable; exotic genera, whilst
differing in various details, are remarkably uniform in the more important
peculiarities of structure, and do not at all tend to bridge the gap. The
relatively large size of the _Hepialidæ_ (of which some species exceed six
inches in expanse of wing) may be attributed to the larval habits, which
render these insects independent of the seasons or fluctuations of
food-supply, thus removing the check which ordinarily limits growth. The
modified type of neuration may have resulted directly from the increase of
size, involving a great strengthening of the main veins beneath the costa
to support the weight. As a consequence of this strengthening, the flight
of the larger species is very powerful, and to this, combined with a choice
of larval food, which is often rather indiscriminate, may perhaps be
ascribed the wide range of the group, rather than to its antiquity. It is
probably of Indo-Malayan origin, and must have existed in that region long
enough to acquire fixity of type before its dispersal, which, geologically
speaking, may not have been exceedingly remote."--(Meyrick.)
There are two genera represented in New Zealand.