AN APPLICATION OF SCANNED FOCUSED ION-BEAM MILLING TO STUDIES ON THE INTERNAL MORPHOLOGY OF SMALL ARTHROPODS

For the first time a scanned focused ion beam of approximately 50 nm d iameter has been used to prepare biological material. Small defined ar eas of the surface were removed by ion etching to allow examination of the underlying structures with a scanning electron microscope. Differ ent milling procedures were carried out on two anatomical features in mites of the genus Halarachne (Halarachnidae: Mesostigmata). In the fi rst, square holes were milled into the surface of the peritrematal pla te to reveal the structure of the underlying respiratory peritrematal groove. In the second, transverse cuts were made: across the shafts of the sensory sensilli which make up the.; sensory Haller's organ on ta rsus I. This latter procedure revealed detail both within the core and walls of sensilli. Details of specimen preparation and milling proced ures, as well as suitability and interpretation of results, are presen ted.