We investigate the production of long-lived metastable (43P2) calcium atoms in a magneto-optical trap (MOT) operating on the 41S0 -> 41P1 transition at 423 nm. For excited 41P1 atoms a weak decay channel into the triplet states 43P2 and 43P1 exists via the 31D2 state. The undesired 43P1 atoms decay back to the ground state within 0.4 ms and can be fully recaptured if the illuminated trap volume is sufficientlylarge. We obtain a flux of above 1010 atoms/s into the 43P2 state. We find that our MOT lifetime of 23 ms is mainly limited by this loss channel, and thus the 43P2 production is not hampered by inelastic collisions. If we close the loss channel by repumping the 31D2 atoms with a 671 nm laser back into the MOT cycling transition, a non-exponential 72 ms trap decay is observed, indicating the presence of inelastic two-body collisions between 41S0 and 41P1 atoms.