28 INSFXT ARTIZANS AND THEIR WORK 



several elliptical cells and line these with saliva 

 which dries into a delicate membrane. The cell 

 is then stored with pollen and honey, an egg laid, 

 and the cell is sealed up. 



One of our species of leaf-cutting bees {Megachile 

 argentata) mines in the earth, unlike its near rela- 

 tions, but as it forms its cells of leaf-cuttings we 

 have included it under the heading Upholsterers, 

 with the other members of the genus. 



Some of the solitary wasps share this habit of 

 mining in order to make provision for their young. 

 In these it is not a mass of pollen that is provided 

 for the food of the future grub. Wasp-grubs 

 require animal matter for their aliment, so the 

 wasp has to hunt for caterpillars or spiders with 

 which to stock the larder. Certain species restrict 

 themselves entirely to spiders, others to grass- 

 hoppers, others again to caterpillars of a particular 

 family of moths. The catching of caterpillars is 

 a simple matter to a wasp, for its prey has no means 

 of protecting itself ; the grasshopper's activity 

 and leaping powers give it a sporting chance ; but 

 the spider has to be approached warily, for its 

 poison- fangs might put it upon equal terms with the 

 wasp, were it not for the wings of the latter, which 

 give it considerable advantage in manoeuvring. 

 However, the wasp has a due sense of the respect 

 to be paid to those poison-fangs, the additional pair 

 of legs, and the possibility of having strong cords 

 wound round one ; she, therefore, resorts to strategy 

 when hunting spiders. 



