ON THE CLASPING ORGANS ATTACHING THE HIND 

 TO THE FORE WINGS IN HYMENOPTERA 



By Dr. LEO WALTER 



WITH TWO FIGURES IN THE TEXT AND FOUR PLATES 



(From the Zoological Institute of the German University in Prague, under the direction 

 of Professor von I,endenfeld. Published with the assistance of the Hodgkins Fund of the 

 Smithsonian Institution.) 



CONTENTS 



. Page 



I. Introduction 65 



II. Historical review 66 



III. Material and methods 67 



IV. Anatomical part 68 



(a) Hind wing 68 



(b) Fore wing 74 



(c) Development of the hooks and the groove 75 



V. Function of the clasping apparatus 76 



VI. Systematic part 79 



VII. Literature consulted 84 



VIII. Explanation of the plates 85 



I. Introduction 



It has long been known that in many four-winged insects peculiar 

 clasping contrivances are present which unite the fore and hind 

 wings during flight in such a manner that they together form a 

 homogeneous surface and act like a single wing. Thus, according to 

 Kolbe (1893, P- 2 55)> many crepuscular and nocturnal Lepidoptera — 

 the Sphingids, Noctuids, Geometrids, Cheloni, and Pyralids — possess 

 a thorn or a group of bristles on the upper side of the base of each 

 hind wing, which inserts itself into a small band-shaped structure 

 formed of hair-scales situated on the under side of the corresponding 

 fore wing near its base, and thus effects the union of the two wings. 

 In the Sesiids, Cicadids, and Trichoptera this union is brought about 

 by the hind margin of the fore wing folding over and interlocking 

 with the inversely folded front margin of the hind wing. The highest 

 development of such a clasping apparatus is met with in the Hyme- 

 noptera. In these, fine chitinous hooks, arranged in a row, arise from 

 the front margin of the central part of the hind wing and insert them- 

 selves into the involuted hind margin of the fore wing. A closer ex- 

 amination, particularly from the morphological point of view, has up 

 to the present never been accorded these structures, and Professor 

 5 65 



