PLATE XX 



f.lKCH (Bctlila alba) with N'UMFKDL'S " Wl ICHES-KR(.lOArS " I'lESULTlNG FICl.tM THE 



I'RESEXCE OK MITES, Rrio/'hyCS rlldis. THIS TJ^EE HAS BEEN UNDER OBSE k\'ATIt )N 



FOR MANY VKAI-:s. THE " l'.KOi>M,s" f^RdW V E !■; V SUtWLY 



