▁for ▁flight , ▁b umble be es ▁need ▁to ▁raise ▁the ▁temperature ▁of ▁the ▁flight ▁mus cles ▁to ▁above ▁ 3 0   ° C ▁( 8 6   ° F ). ▁In ▁B . ▁v os nes ens ki i , ▁heat ▁is ▁transferred ▁from ▁the ▁thor ax ▁to ▁the ▁ab d omen ▁by ▁changes ▁in ▁hem ol ym ph ▁flow ▁in ▁the ▁pet io le , ▁the ▁narrow ▁region ▁between ▁the ▁ab d omen ▁and ▁thor ax . ▁At ▁low ▁ambient ▁temperature , ▁the ▁hem ol ym ph ▁flows ▁from ▁the ▁thor ax ▁and ▁ab d omen ▁simultaneously . ▁As ▁a ▁result , ▁the ▁counter current ▁exchange ▁of ▁heat ▁in ▁the ▁pet io le ▁retain s ▁most ▁of ▁the ▁energy ▁in ▁the ▁thor ax . ▁When ▁the ▁ambient ▁temperature ▁is ▁high , ▁the ▁counter current ▁exchange ▁is ▁reduced ▁such ▁that ▁heat ▁is ▁transferred ▁from ▁the ▁thor ax ▁to ▁the ▁ab d omen . ▁ ▁Diet ▁and ▁Pol lin ation ▁ ▁Diet ▁ ▁This ▁be e ▁species ▁pre fers ▁a ▁select ▁set ▁of ▁gener a ▁for ▁for aging ▁purposes . ▁These ▁include : ▁L up inus , ▁Cir si um , ▁ ▁E ri og on um , ▁Ph ac elia , ▁ ▁Clark ia , ▁and ▁Eric amer ia ▁ ▁Pol lin ation ▁prefer ences ▁ ▁This ▁be e ▁species ▁shows ▁pol lin ation ▁prefer ences ▁based ▁on ▁location ▁and ▁landscape ▁features , ▁as ▁opposed ▁to ▁col ony ▁membership . ▁This ▁indicates ▁that ▁competition ▁between ▁B . ▁v os nes ens