fly ▁of ▁the ▁family ▁Pier idae . ▁ ▁It ▁is ▁much ▁sought ▁after ▁by ▁collect ors , ▁particularly ▁in ▁Austria . ▁This ▁is ▁because ▁one ▁of ▁the ▁most ▁variable ▁populations ▁of ▁this ▁but ter fly ▁lives ▁in ▁the ▁well - known ▁M öd ling ▁area ▁near ▁Vienna . ▁ ▁There ▁has ▁been ▁a ▁long ▁debate ▁among ▁exper ts ▁as ▁to ▁whether ▁it ▁is ▁an ▁independent ▁species ▁or ▁only ▁a ▁sub species ▁of ▁the ▁" green - ve ined ▁white ", ▁Pier is ▁n api . ▁ ▁The ▁type ▁local ity ▁of ▁the ▁nomin ate ▁form ▁is ▁the ▁Al ps , ▁where ▁it ▁is ▁found ▁at ▁considerable ▁alt itudes ▁( up ▁to ▁ 2 0 0 0   m ) ▁and ▁has ▁only ▁one ▁generation ▁per ▁year . ▁Both ▁pairs ▁of ▁the ▁female ' s ▁wings ▁are ▁dark . ▁At ▁lower ▁alt itudes , ▁two ▁or ▁three ▁gener ations ▁appear ▁during ▁a ▁year . ▁Sub species ▁ne ob ry onia e , ▁closely ▁res emb les ▁the ▁Car path ian ▁populations , ▁and ▁is ▁found ▁in ▁the ▁southern ▁parts ▁of ▁the ▁Al ps ▁and ▁s sp . ▁fla ves c ens ▁Wagner ▁inhab its ▁the ▁northern ▁parts . ▁The ▁ground ▁color ation ▁of ▁the ▁wings ▁is ▁yellow ish ▁or ▁rich ▁yellow , ▁often ▁with ▁a ▁m au ve ▁gl oss . ▁The ▁populations ▁inhab iting ▁the ▁Car path ians ▁are ▁very ▁varied . ▁The ▁most ▁distinct ▁ones ▁include ▁the ▁s sp . ▁vi hor lat ensis ▁found ▁in ▁Vi hor lat , ▁the ▁east