Preface. By Dr. A. Seitz. 
11 
we notice such an enormous temporal uncertainty of the flight of Heterocera as we do in the more desolate 
districts of the Ethiopian region. The very same districts that seem for many months and even for years, if 
there is no rain, to be entirely uninhabited and without any insects, may after one of the rarely occurring copious 
rainfalls be crammed with lepidoptera, as not even any of the Indian or Brazilian wood-districts abounding 
in lepidoptera have to boast of. The number of suddenly appearing Noctuids of the most various species may 
then attain such an amount that it cannot be brought in accord with the scanty vegetation which can impossibly 
have been sufficient to nourish such an immense number of larvae. In districts, where on endless collections 
of boulders there is hardly any isolated caper-bush, a Christ’s thorn, a stunted bush of steppe-grass forcing 
its way through the stones, there rise clouds of Heliothis, Prodenia, Cosmophila, Callopistria, Eute.Ua , Ophiusa, 
Tarache etc. in front of the pedestrian. Two days after such a rain, which had fallen after almost two years’ 
pause, I once found near the Bab el Mandeb Strait such immense numbers of Eutelia discistriga , Spodoptera 
abyssinica, Callopistria yerburii, Anna melicerta and Cosmophila sabulifera , that I take it to be quite impossible 
that the legions of larvae out of which they must have developed, had lived at the same time and fed on the 
scanty vegetation. Skertschly reports a quite similar multitudinous appearance of certain butterflies ( Pyra- 
meis cardui), and the only explanation for it I can find is that the Noctuid larvae had grown up in long successive 
periods before and had pupated in the earth at very different times, until the rain made them creep out all 
together, depositing their eggs simultaneously at a time when, as a reaction upon the uncommon rainfalls, 
after a short time the earth was covered with a delicate green veil produced by the vegetation newly awoke 
from its summer-sleep which had lasted for months or years. 
As in the other faunae also in the Ethiopian Region the conditions of the vegetation have the greatest 
influence upon the occurrence of the Heterocera. Beginning from the 10th to the 15th degrees of northern 
latitude to the north as far as the Atlas-countries, Africa is almost treeless, 'and from the Southern Tropic to 
the Cape, wherever the country has not been brought under cultivation, an entirely treeless steppe extends, 
intermixed with low bushes. Tropical woodland being particularly favourable to the development of insects, 
extends from Cape Verde (which itself, however, is still rather barren) to the south in a broad belt as far as 
the basin of the Congo, which it fills up to an immense extent, stretching across a district of 20 degrees 
of longitude and 15 of latitude. Then follows in all directions grass-land being the pasture of immense multitudes 
of game; in some parts it is mixed with dense, thorny hedges and surmounted by single, partly gigantic trees, 
mostly Mimosae, Acaciae, and sycamores, or also studded with palms. A dense, but less broad forest-belt covers 
the coast opposite Madagascar and this island itself even as far as its most central, alpine part which is still 
little known. 
The whole western coast of Africa, from Loanda to Cape Town, is sandy country. Excepting a very 
short grassy part in the more humid districts, the country is yellow, dry and burnt. Barren, stony soil, in 
some places undulating like downs, bordered by bare, rocky hills in the interior. From there a wide, hot plain, 
the ,,Buschvelt“, extends towards Bechuanaland, growing more and more desolate and barren, as far as the 
partly quite dead Kalahari Desert. Only in the direction of the Karroo and the plains near Pretoria there 
begin again richer pastures, and only in Natal and Transvaal complete forests set in again, though they are 
frequently' not very extensive. 
The DesertFaunais nothing but a scanty residue composed of few tenacious but mostly stunted 
forms of the lepidopteral fauna. Particularly'- cosmopolitans penetrate into the bare deserts from the neighbouring 
countries, which presumably are also often dying out. though they are supplemented again by new accessions. 
Utetheisa pulchella, Nemophila noctuella, species of Grammodes and Anna are to be found yet in the scanty 7 bushes 
which are the last branches of the vegetable kingdom, vanishing in the sands like advanced outposts. 
This scanty desert-fauna is opposed by that of the Highland-Savannas-, it is not rich in species, but 
in specimens, the flying-time of which is mostly very short. Of the Heterocera mostly small species belong to 
it; but wherever the brushwood becomes more abundant, where the scattered gigantic trees with their frequently 
far expanded crowns protect the humid soil a little longer from the parching rays of the sun, they are already 
joined by larger forms of Sphingidae, large Nocluidae, and diurnal Agaristidae, Syntomidae and Arctiidae. 
The transition of this second group to the last and richest, the Forest-Fauna, already takes 
place •— as Arnold Schltltze states — where the first portions of forests begin, even if they are yet separated 
from the real Hylaea by interspersed steppes of a considerable extent. This last, third fauna of the forest- 
district is by far the most exuberant, and wherever alternative mountainous countries or deeply indented valleys 
of rivers make the primeval forests thinner in some places, we meet in nearly all parts of Equatorial Central 
Africa with that abundance of lepidoptera which we have mentioned above to attain or even exceed that of 
many Indian and South American regions that are celebrated as being very 7 rich in insects. 
The lepidopteral fauna of Tropical Africa is very strangely independent of the adjoining fauna of 
Madagascar, which exhibits remarkably little resemblance with the neighbouring African litoral, in which, 
however, many authors have noticed a strong leaning to the Indian Fauna. On examining the species of 
