Surely that depends on the leverage and linkage mechanisms used? It has a stall torque of 1kg/cm on 4.8V and my arm is only going to be a straight beam around 3cm long, so that gives a lift capability of roughly 250g at stall, and slightly less under normal operating conditions.

It doesn't actually need to lift an ant if it stays within the fleaweight category but I'm sure I used one of these in an obese ant I made a good four or five years ago and it coped with lifting 150g alright. Guess I'll find out when I get it working :P