386 



FOREST ENTOMOLOGY. 



wards applied, the valuable object has often been found outside the 

 cover-glass in the superfluous balsam, so that mounting carefully the 

 opposite way generally gives better results. 



With regard to the preparation of the larger specimens, as, for 

 example, the female scales of Lecanium and Pulvinaria, they may be 

 boiled in caustic potash in a test-tube (not in an inner one, as with 

 the very small species), then boiled in clean water, then transferred 

 to absolute alcohoP with stain for a day, oil of cloves for another 

 day, and finally mount in xylol balsam. 



In addition to studying the more salient points of the anatomy of 



Fig. 352.— Life-history stages of " ti wallow-tail" Butterfly (Fa\>\Uo inachaon). 

 (Photo from specimens prepared by Mr L. Greening, Warrington.) 



forest insects, the student would do well to study the details of 

 minute insect structure as revealed by microscopical investigation. 

 There is obviously no end of objects outside forest insects, thus giving 

 the student not only a wider outlook, but teaching him many a 

 valuable lesson from indirect subjects. Take, for example, the case 

 of figs. 350 and 351 — the proboscis of the honey-bee and the tongue 

 of the house-fly. Not only do subjects like these show marvellous 

 mechanism, but they throw a strong sidelight on such delicate ana- 

 tomy as the mouth parts and feeding organs of scale-insects, green-fly. 



^ It is best, in many cases, to begin with diluted alcohol and 

 strengthen it to absolute alcohol. 



radually 



