We　report　here　on　terahertz　(THz)　digital　holography　on　a　biological　specimen.　A　continuous-wave　(CW)　THz　in-line　holographic　setup　was　built　based　on　a　2.52　THz　CO2　pumped　THz　laser　and　a　pyroelectric　array　detector.　We　introduced　novel　statistical　method　of　obtaining　true　intensity　values　for　the　pyroelectric　array　detector＇s　pixels.　Absorption　and　phase-shifting　images　of　a　dragonfly＇s　hindwing　were　reconstructed　simultaneously　from　single　in-line　hologram.　Furthermore,　we　applied　phase　retrieval　routines　to　eliminate　twin　image　and　enhanced　the　resolution　of　the　reconstructions　by　hologram　extrapolation　beyond　the　detector　area.　The　finest　observed　features　are　35　m　width　cross　veins.　(C)2014　Optical　Society　of　America