THYRIDIDAE. General Topics. By Dr. A. Seitz. 
743 
Family: Thyrididae. 
Regarding the general topics of this family, about which little is to be said for the reasons stated in 
Vol. XIV (p. 489) we refer our readers to that place as well as to Vol. II, p. 371. We had also mentioned 
there the great difficulties of classifying this family in the system where it is placed between the Macrolepi- 
doptera and the Microlepidoptera; this intermediary position is expressed by Hampson by inserting them be¬ 
tween the Drepanidae — to which they are supposed to be related — and the Pyralidae to which they are un¬ 
mistakably allied. Judging especially from the very poor facts we kown of them, the life-habits of both the 
larva and imago are exactly those of Pyralidae, and both the flight and the attitude in repose, the way of rest¬ 
ing on high legs thin as hair in an almost Tipula-like attitude, above all the spread out wings, exactly like 
certain Pyralidae do (e. g. the cosmopolitan Maruca testulalis), are too individual to urge on us the thought of 
convergency. 
The family is almost equably distributed over the Old and New World. It is mostly tropical, and the 
species decrease so quickly towards the polar regions that only 1 species reaches the European continent, while 
only 3 or 4 inhabit the north of Asia, not even 20 forms occurring in the whole palaearctic region; in America 
only 4 reach the Northern United States, and 6 others cross the northern frontier of Mexico. The whole rest, 
more than 200 Indian and just as many neotropical species are bound to the warm climates. 
The Thyrididae are no common lepidoptera. Hardly any tropical species occurs in such numbers as 
the European Thyris jenestrella, and even this species is by no means everywhere common, where it occurs. 
Many species of the foreign — especially also the Indo-Australian — Thyrididae are great rarities; not only 
in the collections, owing to the difficulties of discovering them, but because the individuals are in fact extra¬ 
ordinarily rare. Just the larger, more variegated and conspicuous species are mostly so shy that they fly up 
before the collector’s feet or come forth at the slightest tap on the bushes, so that there is hardly any possi¬ 
bility of ascertaining many of them. Others swarm generally in the daytime in the sunshine, and nearly all 
have a so very characteristical, quite unmistakable exterior that the careful and expert collector may be sure 
of noticing all the specimens present on his route. Nevertheless the collector may wander through the country 
for months and months without having observed a single Thyridida. The Thyrididae also come to the lantern 
in the evening, but very rarely certain species are collected in any greater number, but almost invariably only 
single representatives of this family are captured in the evening. 
We have already spoken in Vol. II and XIV about the variability of shapes of the Thyrididae. Beside 
plump and stout species which in flying might be taken to be beetles*), we find Pyralid-like slender forms 
with thin legs, such as Rhodoneura strigatula (Vol. II, pi. 50 f) or Geometrid-like slender species with broad 
wings **). Very many, even dissimilarly shaped genera preferably exhibit small vitreous spots, particularly in 
the hindwing, which however vary considerably in size and may be extensive or also quite absent even in indi¬ 
viduals of the same species. Moreover, some species show a “carpet-like pattern”, as Pagenstecher expresses 
himself, owing to peculiar striation and strange reticulate markings, whilst the colouring of others makes an 
almost archaic impression, so that they might be regarded as remainders from ancient epochs of creation. 
The various organs — such as antennae, palpi, legs — of the Thyrididae do not exhibit a homogeneous 
structure, and the shape of the wings also shows great differences. Sometimes all the four wings are extended 
into long apices, as for instance in the American Draconia mirabilis Pagst. ; the forewings of others are convex 
upwards and the costal margin is very protuberant, as in the pinkish red Risama picta Wkr. ; others exhibit 
*) Cf. the figure of Dysodia ignita (Vol. II, pi. 50 e). 
**) For instance Herd'onia osacesalis (ibid.). 
