  We investigate the behavior of a treadmilling microswimmer in a
two-dimensional unbounded domain with a semi-infinite no-slip wall. The wall
can also be regarded as a probe or pipette inserted into the flow. We solve the
governing evolution equations in an analytical form and numerically calculate
trajectories of the swimmer for several different initial positions and
orientations. We then compute the probability that the treadmilling organism
can escape the vicinity of the wall. We find that many trajectories in a
'wedge' around the wall are likely to escape. This suggests that inserting a
probe or pipette in a suspension of organism may push away treadmilling
swimmers.
