PREPARATION AND EQUIPMENT NEEDED FOR IDENTIFICATION 



For identification of genera or species, a stereoscopic microscope, spot 

 lamp, forceps, and fine needles are necessities. Disposable hypodermic 

 syringe needles (e.g.. No. 26) attached to any convenient handle make 

 excellent micro-scalpels. All dissections and most examination of 

 material, particularly of larvae, should be done with the specimen 

 immersed in water or alcohol. For specific determination in some genera, 

 such as Stenelmis^ it is necessary to extract the male genitalia and to 

 mount them on a microscope slide for examination under a compound micro- 

 scope. Glycerol (glycerine) is satisfactory for temporary microscopic 

 preparations. Hoyer's mounting medium (obtainable from Ward's Natural 

 Science Establishment, Rochester, New York) is quite convenient for 

 temporary and semi-permanent mounts. Canada balsam is perhaps best for 

 permanent mounts, though it is time-consuming, since specimens must be 

 completely dehydrated through a graded series of alcohol concentrations, 

 then saturated with a suitable solvent such as xylol or toluol, before 

 placing in the balsam. 



Most specimens as brought in from streams are well covered with either 

 mineral deposits (sometimes far exceeding the weight of the insect) or 

 epizoic organisms such as diatoms and peritrich ciliate protozoa. A 

 sonic cleaning tank is helpful, but removes only the rather loosely- 

 adhering "dirt". A closely-trimmed camel 's-hair brush is also quite 

 useful in cleaning specimens, but often only breaking of the mineral 

 "armor" with forceps or scraping with a needle can reveal the surface 

 of the insect. Care must be exercised in such scraping, for it is easy 

 to scrape through the cuticle and artificially produce misleading mark- 

 ings or coloration. 



When required for specific determination, genitalia may be removed in 

 at least two ways: (1) using a stereoscopic microscope to observe, hold 

 the specimen between the thumb and forefinger of one hand; with fine- 

 tipped watchmaker's forceps in the other hand, insert the tips between 

 the last abdominal stemite and elytral apex (Figs 1, 2); grasp and ex- 

 tract whatever you can. With a little experience, one can usually 

 remove the genitalia by this means. The other method is usually more 

 destructive to the specimen. (2) Remove either the abdomen (it can 

 often be glued back into place if necessary) or the elytra. This 

 exposes the soft dorsal tergites of the abdomen, through which an 

 incision can be made - or the whole dorsum torn off- to expose the 

 underlying visceral organs. Usually the only prominent sclerotized 

 structure in the abdomen of the male is the genital complex. This can 

 be removed and teased apart in appropriate fashion. As a rule, the 

 soft enclosing tissues must be torn away, along with the penial spicules 

 (Fig. 10) in order to expose the genitalia. Further cleaning and clear- 

 ing can be accomplished by placing the genitalia in a hot aqueous 

 solution of strong potassium hydroxide for about 15 minutes. After 

 rinsing in distilled water, then 70% alcohol, the specimen may be 



