PSYCHID.E. — Introduction. By Dr. A. Seitz. 351 



22. Family: Psychidae. 



The family of case-moth.s comes clo.se to the Heferogynichie in the acquired adaptations, but not in its 

 anatomical structure and systematic affinities. Where its proper position in a scheme of classification should 

 be, is the less possible to say, as the family is not homogeneous and the characters on which the systematic 

 position has hitherto been based are for the most part taken from superficial adaptations to a life in cases 

 which have rendered originally differently organised moths similar. Some genera would certainly be best 

 referred to the Micros, if one does not go so far as to separate from the Macros the whole group as being 

 more or less closely related to the Micros, as is also the case with the Sesiidae, Thyrididae and others. 



We follow also here the general use and place the Psychidae where they are found in the hand-books, 

 particularly in the excellent C^atalogues of W. F. Kirby and Staudinger-Rebel, namely in the neighbourhood 

 of the Limacodidae and Sesiidae, being separated from them only by small and relatively isolated groups 

 which had to be interpolated. 



It follows from what we have just said that the characterisation of the family cannot very well be based 

 on the structure. But the species have many bionomic points in common, and it is also advisable from a prac- 

 tical view-point to base the arrangement on the external adaptations until a detailed anatomical examin- 

 ation enables us to place the various groups of Psychidae with those other families with which they are 

 phylogenetically related. Such families are perhaps the Megalopygidae, Limacodidae, Tineidae (resp. Talaeo- 

 poridae) and probably also the Lithosiidae, presumably also some others. 



The Palearctic Psychidae are all small and incon.spicuously coloured moths, as are also most of the exotic 

 forms (of which, however, only an insignifant fraction is known). There are no really bright-coloured species 

 at all. The only vividly coloured Psychid is probably Metura elongata {Oiketicus saundersii) from Australia, 

 whose wings are russet black-brown and reticulate, while the head and thorax are very vivid orange-yellow, 

 the two colours contrasting strongly. Some Bolivian species have entirely vitreous wings, and even in the 

 largest forms the scheme of marking is the simplest imaginable. 



The most striking characteristics of the family are the reduction of the 9$ and that the larvae live 

 in a protecting case. The exceedingly numerous eggs, of which many hundreds are laid by a $, are globular 

 and small, almost equalling coarse sand. They lie in the maternal case embedded in a kind of .spun wool 

 and remain undeveloped for months in some species. The young larvae resemble minute Staphylinid beetles. 

 As they are without abdominal legs, their thoracic legs are strongly developed instead, and the young larvae 

 when disperseing raise the abdomen, as do the Staphylinidae when irritated. The young caterpillar has a 

 flat, hard and horny head and the 3 thoracic segments strongly chitinised, the abdomen being soft. Soon 

 after leaving the maternal case it commences to bite off little bits from all kinds of objects and, by uniting 

 them, to build a very primitive protecting ca.se. I used to give the young larvae hits of cork, for which 

 they show a great preference and which they only discard at a later stage in favour of little pieces of 

 leaves, stalks, etc. The sti'ucture of the case is usually characteristic for each species. At large it is constructed 

 according to species of bits of leaves, twigs, stalks, moss, lichen, sand, small flints, small shells, etc. ; but in capti- 

 vity all kinds of artificial products are spun into the case, such as cloth, paper and even minute particles of metal. 

 Almost during the whole larval period the caterpillar is occupied with enlarging, repairing or renewing the case. 

 The larva is able to turn in the case freely, and can alter the case in every place as it thinks fit, biting a hole 

 into the case from inside in order to remove a piece of cover which is no longer suitable and to replace it by 

 another object. When rearing hundreds of caterpillars of the large Oiketicus geyeri, which I have done for 

 years, I changed sometimes the material mixed with the food-plants and thus obtained cases consisting some- 

 times more of cork, or particles of leather, sometimes more of bits of newspapers, etc. Sometimes the larvae 

 turned thieves, biting off particles from the cases of others and using them for themselves. 



Whatever the characteristic of the case may be m a species, the individuals of this species hardly 

 differ among themselves in their building instinct. With a certain species some material for building may 

 be much preferred, oth?r material altogether rejected, but I was often astonished in noticing how uniform 

 were the cases of the specimens of a .species even if the individmals fed on quite different pltints. I sometimes 



