210 THE UNIVERSE. 



Having carefully extracted several of its larvae from their 

 shelly sheaths, and afterwards placed them in vessels of 

 water, the bottom of which was covered only with little 

 pearls of various colours, I saw them immediately set to 

 work to make a new residence, choosing here and there 

 pearls of the most different hues, in such a way that when 

 the construction was finished, each Phryganea's dress re- 

 sembled a little case in mosaic, promenading on the walls 

 of my crystal vase. 



Other insects, instead of these portable abodes, labori- 

 ously hollow out for themselves a refuge in the hardest 

 bodies, even metals. The most extraordinary animal of 







127. Sheath Phryganea— P/wv/^a/fca striata (Linnfeus). Larva and Adult Insect. 



this kind that is known is a powerful hymenopter, the 

 Giant 8irex, the larva of which, during our expedition to 

 the Crimea, gnawed the balls in the soldiers' cartridges 

 and bored deep holes in them in which it might find a secure 

 shelter. Marshall Vaillant presented to the Academy of 

 Sciences several balls which had been pierced through in 

 this Avay by the unknown pluml^er. 



Several of these metal-eaters are known; men were pre- 

 viously aware that the larvae of one Cetonia sometimes 



