48 COLLECTING AND PRESERVING COCCIDjE. 



As the external characters presented by the puparia 

 of many species are identical ; the student will find it 

 necessary at all times to examine microscopically the 

 minute structural characters of the insects. To enable 

 one to do this the insects must be treated with various 

 reagents and permanently mounted. The materials 

 required are 



1. Ten per cent, solution of caustic potash (KOH). 



2. Distilled water. 



3. Absolute alcohol. 



4. Stain ; for this I prefer " Crawshaw's magenta," 

 which is sold in small packets. 



5. Oil of cloves. 



To prepare the Diaspinae scrape off a quantity of 

 the puparia (scales) into a sheet of white paper, and 

 either place the whole of this, or better still select 

 from the debris, the desiccated bodies of the insects; 

 place them in a small tube, fill it up with the caustic 

 potash, and plug with cotton wool. Place the tube 

 with the specimens inside a test-tube and half fill with 

 the caustic potash. Label the specimen (using a lead 

 pencil), and either set aside in a test-tube stand or at 

 once place it in a hot water bath. If necessary several 

 species may be treated at the same time. Larger in- 

 sects, such as Lecanium, Dach/lopius, etc., may be 

 placed in a test-tube. Boil the tube or tubes in a hot 

 water bath until the insects are* more or less trans- 

 parent, which takes from one to twenty minutes ac- 

 cording to the opacity of the insects, or rather the 

 solubility of the body fats. With the larger speci- 

 mens it is advisable to prick them with a needle 

 in order to liberate the fats, etc., and subsequently 

 shake them in a test-tube of water. In all cases 

 thoroughly wash in two lots of distilled water, and 

 afterwards 



(a) Transfer to equal parts of alcohol and water ; 



(/>) To absolute alcohol for a few seconds ; 



(c) Stain with magenta stain dissolved in alcohol ; 



(d) Wash in alcohol ; 



