O 
INTRODUCTION. By Dr. A. Seitz. 
active by day. While the great majority of the Noctuids and especially most Bombycids and Sphingids pass 
the day in such a lethargic condition that one can approach, and mostly indeed even touch them without alar¬ 
ming them, the slightest shaking of a branch or twig, often indeed a mere incautious approach, suffices to 
make the Geometrids take wing. A not inconsiderable number fly chiefly by day in the sunshine and Dysphania 
are even among the most shy moths known to me and in order to catch them it is necessary to creep up very 
cautiously, even when they are feeding at flowers. The moths must, moreover, have very good sight, for some 
fly up to a height, like an Orgyia, as soon as they are chased. 
The Geometridae commonly evince a very marked need of water. One notices that they have a predi¬ 
lection at night for flying in damp, moist thickets, in the true jungle, and they may be found commonly drin¬ 
king at damp spots before the sun has evaporated the dews. In certain species of Pantherodes in America it 
has been observed that they regularly purge themselves with water so that when they are drinking at the pools 
or brooks the water taken in is always ejected again at the anus. DukiNfield Jones counted 50 large drops 
of water which one of these Geometrids passed in a.minute and he estimates the amount of water which 
would pass through the abdomen within three hours at two hundred times the weight of the body. 
At rest, as stated in more detail in the Introduction to Palaearctic Geometridae, the majority of the Geo¬ 
metrids are protectively coloured; some exactly assimilate to the bark of the tree on which they settle, being 
greenish like the lichen or grey like the bark, and are finely speckled, so that only the outline of the wing 
betrays them. But even here the difficulty of recognizing them is often increased by a remarkable habit 
of the species. Certain species of the Indian Pingam, which are fond of sitting on fences and palings, rest 
with the forewings in about the position which they assume in our modern system of setting, while the hind- 
wings are withdrawn to the abdomen; there is thus between the fore- and hind wing a wide space in which 
the uncovered surface of the background shows. In this way an impression is created of a half moth, or still 
more of a fore and a hinder half which do not fit well together. The giant Medasina of tropical India, 
which reach upwards of 10 cm. expanse, are fond of sitting on rather narrow stems, but as in the normal resting 
posture the tips of the icings would project beyond the tree-trunk and reveal the insect they are obliged to 
settle sideways with the body horizontally placed and one pair of wings spread out above, the other below. 
The larvae are no less protected than the imagines and are often so difficult to detect that one has to 
touch them in order to distinguish them with certainly from a twig or a leaf-stalk or the like. They al¬ 
ways, however, betray their identity by the peculiarity of their gait, the ,,looping” progression to which the 
family owes its name (,,Geometer”, ,,grounclmeasurer“) and which further appeared to the ancients the most 
striking among all the lepidopterous larvae, so that in Greek the larva itself was designated xaprcrj, i. e. ,.ben¬ 
ding insect”: the bent posture of the Geometrid larva giving allegorically the antithesis to the liberated soul 
(-jiuy/J, the light-winged imago. 
Almost all the Geometrid larvae are so slightly haired that it would be possible to describe them as 
,,glabrous” or ,,naked”, but they often develop fleshy processes, warts or knobs, which deceptively resemble 
similar formations on the foodplant and do good service in protecting their possessors. 
On the distribution of the individual genera and the relative development of the subfamilies in the 
separate countries of the Indo-Australian Region, no definite data can be obtained, so long as the division 
into the subfamilies is treated in such contradictory ways as has been the case up till quite recently. A satis¬ 
factory cataloguing of the family has only just been commenced (L. B. Proitt, in Lepidopterorum Catalogus). 
Sampson had earlier (in his General system. List Heteroc. Ceylon) maintained numerous subdivisions of the 
family to which we cannot deny some justification but which have mostly now been abandoned; thus Eumelea 
was kept separated as ,,Palyanae“, Dysphania, as ,,EuscJierninae“, Abraxas as ,,Zereninae u , etc.; all groups 
which today are arranged in the large subdivisions referred to above. 
Of the first subfamily, the Oenoclirominae , nearly three fourths inhabit the Indo-Australian Region, 
for the most part Australia itself or New Zealand. Tt may justly be suspected that Australia is the centre 
of distribution of the subfamily, since several of its genera, such as Dichromodes and Taxeotis, each with 30-—50 
species, are entirely confined to Australasia *); indeed of the 100 genera of Oenoclirominae , over a third, with 
almost 200 species, have not yet been found at all outside Australia. India with the Archipelago produces 
only a little more than 100 species, but these mostly surpass the Australian in beauty and bold colouring. 
For the other faunas the subfamily is almost negligeable, and on closer study its delimitations can be brought still 
more into unison with zoogeography. Of the 30 or 50 palaearctic species very many are only provisionally 
placed here, the American genera belong mostly to one of the lateral branches ( Ametridicae or Hedylicae), 
*) We sometimes find the view held that some of the islands to the north of the continent also belong to 
Australasia; this is erroneous; Australasia signifies the Australian continent and Tasmania and New Zealand collectively, 
in contradistinction to Australia, itself, which only embraces the 5 colonies of the mainland. 
