COSSIDAE. General Topics. By Dr. A. Seitz. 
807 
25. Family: Cossidae. 
Already in Vol. II (p. 417) we pointed out how very little we know of this family owing to the 
secluded habits of its members. From 200 Cossicl forms known at the end of the last century (cf. Vol. XIV, 
p. 53) their number has increased to more than 500 to-day, from which fact we may infer the great number 
of species which will yet be discovered. Nevertheless the number of species ascertained in the more extensive 
districts is very different, though much less owing to climatic differences than to the dependency on the 
geohistorical age of the various countries. At the place quoted above (Vol. II, p. 417) we had already called 
the reader’s attention to the archaic age of the Cossidae, according to which the greatest abundance in 
Cossidae is met with in the geologically oldest countries, so chiefly in Australia and Central Asia, the former 
country being included in the range of the fauna dealt with here. In Australia we also find the largest species 
of the family, the larvae of which live in the gigantic trunks of Eucalyptus and in the wood of tall Simarubeae, 
such as Ailanthus; the immense volume of the body can be seen from our figures on pi. 97 and 98. 
Regarding the general characteristics of the family we may refer the reader to the places quoted 
above (in Voll. II and XIV). All the larger Cossidae are generally provided with uncommonly hard wings, 
contrary to most of the Hepialidae of which only some genera (such as Abantiades) have stiff, solid mem¬ 
branes of the wings, and contrary also to the otherwise Cossid-like Metarbelidae■ and Indarbelidae which exhibit 
an especially delicate and sensitive substance of the wings. 
Considering this robustness of the wings enabling them to fly for long distances it is rather strange that 
the range of a great number of Cossidae is very limited on the Earth. Especially the smaller species, such as 
those of the chiefly palaearctic genera Dyspessa and Holcocerus, often do not leave their restricted range, 
although it has been proved that they are very frequently imported to other countries, which is easily ex¬ 
plained by the habits of the larvae living in wood resp. in the stalks of reeds or grasses. The numerous 
palaearctic Cossidae of Eastern Asia are also very easily distributed southward by the almost annual inundations 
in Indo-China, during wich the enormously rising gigantic rivers take away big trunks of trees of all kinds 
as well as whole islands that have been torn off from the banks, floating far down to the south through 
Siam and Cambodja. But regarding the northern Cossidae only the Cosstts-like Holcocerus vicarius has been 
ascertained in Tonkin so far, besides the species Phragmataecia castaneae , which is distributed over almost the 
whole of Asia and Europe, and (the southern) Xyleutes. This distinct limitation of the range can only be 
explained by the fact that the insects imported to foi’eign districts are opposed by certain enemies impeding 
their progress, for the Cossidae are not very sensitive to climatic influences. 
Most of the Cossidae are apparently not protected by interior saps, so that they fall the victims to 
birds, especially to bats. Only the Zeuzerinae, which also contrast with the Cossidae in the habitus and 
morphologically to such a degree that the opinion of some authors considering them to be separate families 
has much in its favour, are generally scorned by some insectivora (such as chickens) and therefore have a 
warning colour, as for instance the metallic blue-spotted Zeuzera indica (96 a), coffeae (96 b), and others. 
Against diurnal animals — particularly reptiles and birds — the greatest part of the Cossidae are 
protected by a remarkably minute adaptation to their surroundings. We had stated in Vol. II at the place 
quoted above that the veins of the bark are preferably copied by them. The colour and marking of the 
wings of Cossus cossus, for example, are so exactly likened to the bark of willows on which the lepidopteron 
rests that it can only be discovered by the contours of its shape projecting from the b^rk. And even this 
treacherous behaviour is neutralized in some countries — as Mr. Karl Dietze has illustrated in a figure (i. 1.) 
