atia ). ▁ ▁Great ▁Britain ▁It ▁is ▁Britain ' s ▁only ▁true ▁al pine ▁species ▁of ▁but ter fly . ▁The ▁lar va ▁fe eds ▁on ▁mo or ▁mat gr ass ▁near ▁b ogs ▁and ▁spr ings ▁and ▁the ▁ne ct ar - feed ing ▁adult ▁vis its ▁bil berry , ▁tor ment il ▁and ▁he ath ▁bed st raw . ▁ ▁Life ▁history ▁The ▁pale ▁cre am ▁eggs ▁are ▁laid ▁sing ly , ▁each ▁female ▁lay ing ▁up ▁to ▁ 7 0 . ▁The ▁egg ▁stage ▁last s ▁two ▁or ▁three ▁weeks . ▁ ▁The ▁lar va ▁is ▁green ▁with ▁a ▁double ▁d ors al ▁and ▁a ▁single ▁later al ▁white ▁or ▁yellow ish ▁line . ▁The ▁third ▁inst ar ▁lar va e ▁hibernate ▁in ▁grass ▁t us so cks . ▁They ▁emer ge ▁in ▁the ▁spring ▁and ▁recomm ence ▁feed ing . ▁Some ▁lar va e ▁spend ▁two ▁years ▁in ▁this ▁stage , ▁the ▁result ▁of ▁a ▁late ▁spring ▁and ▁short ▁summer ▁restrict ing ▁growth . ▁Record ed ▁lar val ▁food ▁plants ▁are ▁A ira ▁pra ec ox ▁( C zech oslov ak ia , ▁Spain ), ▁D esch amps ia ▁ces pit osa ▁( C zech oslov ak ia ), ▁Fest uca ▁ov ina ▁( Sp ain ), ▁N ard us ▁strict a ▁( B rit ish ▁Is les ) ▁and ▁Po a ▁ann ua ▁( Sp ain ) ▁ ▁The ▁pup a ▁is ▁formed ▁deep ▁in ▁grass ▁t us so cks , ▁enc ased ▁within ▁a ▁loose ▁sil k