A CENTURY OF LARVAL DESCRIPTIONS. 37 



A century of larval descriptions. 



By HAEEISON G. DYAE, Ph.D. 



At the beginning of the century there were extant the results of 

 some twenty-five workers on lepidopterous larvre, covering a period 

 of about fifty years, from the writings of Eosel von Rosenhof (1746) to 

 Hiibner and Sepp, whose Avorks were not finished till well into the 

 century. The descriptions find figures of this period refer mainly to 

 European lepidoptera, though references are not Avanting to those of 

 other parts of the world. The characterisations are mostly, as would 

 be expected, of a general descriptive nature, varying from a few words 

 only, as those of Linne and Fabricius, to fairly complete ones, some of 

 Avhich, as Dr. Ernst Hofmann remarks (preface to liattpcn Gross- 

 ScJniictt. Eiovpas, 1898) would pass muster to-day. 



During the hundred years that have elapsed since, about a hundred 

 additional authors have written on lepidopterous larvae. The principal 

 result of their efforts has been to make known the general appearance 

 and habits of a considerable portion of the species inhabiting Europe 

 and North America. Those of the other parts of the world are noAV about 

 as nearly unknown as they were at the beginning of the century, 

 though some progress has been made in India and Australia. 



In Europe the percentage of known larva? in 1800 did not exceed 10% ; 

 to-day it has increased to about 70%. In North America the increase has 

 been from 1^% to 20%. In general the larger butterflies and the smaller 

 Tineids have been best Avorked up. The former from their large size 

 and comparative fewness of species, the latter because they are best 

 collected as larvae. With the Tineids, however, many of the descrip- 

 tions are not more than records of habits and food-plants, since the 

 small size of the larvte and their obscure modes of life render them 

 difficult of observation. As to the fauna of the world, but a small 

 beginning has been made. We note from Hampson's first volume of 

 the Catalof/iie Lcp. Phalacnae Brit. Mitn. (on the Syntomiilae of the 

 Avorld) that only 2% of the species are knoAvn in their larval stages. 

 All the European forms are known (allowing for the species of 

 DtjmK.ri'ti, Avhich are not referred to by Hampson, though known) and 

 50% of the North American, while less than 1% from other parts of 

 the world have been observed. In the second volume {Xolickie and 

 Lithdsiiilae) there is a somewhat better showing, 3^% of the world 

 species being referred to, but less than 1% from regions outside Europe 

 and North America. There is certainly a great field here for students, 

 especially when travelling in foreign lands. 



The completeness with which the larvae have been described has 

 varied greatly Avith the ideas of different authors. Some, CA^en to-day, 

 have scarcely advanced beyond the diagnoses of Linne, Avhile others have 

 published A-ery full and complete descriptions. AdA^ance has been most 

 marked in this dii'ection in the last ten years. As used simply for 

 purposes of recognition, it depends much upon the family or genus of 

 a given insect as to hoAV full a description is needed. ]\Iany of the 

 larger and conspicuously coloured larA'a? are so different from each 

 other that a comparatively few Avords Avill define them, Avhile others, 

 if not absolutely identical, are yet so similar, that the utmost care and 

 detail arc required to dillerentiate them. These circumstances should 

 be, but unfortunately have not always been, reflected in the descrip- 



