COSSIDAE. General Topics. By Dr. A. Seitz, 
539 
23. Family: Cossidae. 
The Cossidae or typical wood-borers exhibit all the peculiarities of a phylogenetically old family. They 
have, according to Packard, probably developed from a side-branch of the Tortricidae, and — as larvae, pupae, 
and imagines — they merely represent such a branch with much larger forms, since the assumption of their 
direct descent from still existing Tortricid genera (cf. Vol. II, p. 417) has been strongly objected to. They may 
bear a similar relationship to the Tortricidae as the Myelobiidae (genus Morpheis ) do to the Crambinae. Thus, 
for instance, the larva of Cossus exhibits the flat structure of Tortricidae living in cornets made of leaves, and 
the larva of Myelobia the round body of the Pyralid larvae. 
It may be due to their feeding from the wood of tropical trees which are succulent throughout the year, 
that the Cossidae of the genus Xyleutes (Duomitus) often attain an enormous size. An expanse of more than 
200 mm is by no means rare with Indian and Australian Cossidae, and even the X. leuconotus which reach 
the palaearctic region (Vol. II, pi. 53 a) are almost as large. African species are still considerably larger, for 
whilst the of X. leuconotus has an expanse of only 80 mm (the size of a Cossus cossus-Q), the £ of X. moderata 
from the Lion Coast already shows an expanse of more than 140 mm. 
We can easily distinguish different types of lepidoptera among the Cossidae ; they deviate so much from 
each other that even the homogeneousness of the family is doubted and some lepidopterologists are of opinion 
that the characteristics common to the family are for the greater part merely to be considered as resemblance 
by convergency, produced by the endophyte habits of the larvae. Above all, the genuine Cossinae were separated 
from the Zeuzerinae exhibiting quite differently structured antennae. Thus the C antenna of Zeuzera is long- 
pinnate in its basal portion and provided with a long bare terminal whip, entirely unlike the bipectinate $ 
antenna of a Cossus. But the more new forms we find of this family as yet incompletely known, the more 
intermediary forms appear between the two kinds of antennae. Moreover, these differences are also opposed 
by numerous remarkable conformities of all the various Cossid types. For instance the extraordinarily hard 
wings, the solidness of which is unparalleled in the whole lepiclopteral kingdom and even excels by far the 
hard wings of the Sphingidae. The stunted growth of the stomatic parts which is not only expressed by the 
entirely stunted proboscis but also by the reduction of the palpi which are often closely appressed to the face, 
the very large eyes which are below only separated by a narrow stripe of the face and almost resemble the 
contiguous eyes of some Hepialidae\ the considerable difference in size between the two sexes and the C6 
of the same species, the fatness of the body which after the death of the insect almost invariably causes it to 
become oily, the entirely nocturnal habits and the very late flying-hour of the imagines, and many other 
characteristica which may frequently occur in the Heterocera though seldom so jointly, were the cause of the 
Cossidae continuously being treated as a homogeneous group united by interior relations. 
The phylogenetically very old age of the Cossidae is besides proved by the absence of the proboscis, 
the primitive neuration, the habit of shunning the light, and other characteristics. Nor is it refuted by their 
exterior which is monotonous to a certain degree, at least within the different genera, since the intense adaptation 
to the protecting surroundings forces the imago to copy certain features (as for instance the bark-like veins 
of the wings) in the same way as it forces all the larvae to live in the interior of plants. Many forms of Cossus 
are so much alike that their specific difference was doubted for well founded reasons. The most essential fact, 
however, arguing in favour of the long existence of the Cossidae in our creation, is the world-wide distribution 
of nearly all the genera that are not monotypical or oligotypical, occurring in the remotest places of our earth 
in hardly deviating forms. 
Moreover, it may be considered that the opportunity of wide distribution is particularly great in the 
case of the Cossidae being wood or pith borers. Trunks of trees are broken off from banks during the course 
