  We discuss the second order contributions to lensing statistics resulting
from the clustering of background sources from which galaxy shape measurements
are made in weak lensing experiments. In addition to a previously discussed
contribution to the lensing skewness, background source clustering also
contributes to the two-point correlation function, such as the angular power
spectrum of convergence or shear. At arcminute scales or above, the second
order contribution to the angular power spectrum of convergence due to source
clustering is below the level of a few percent. The background clustering of
sources also results in a non-Gaussian contribution to the power spectrum
covariance of weak lensing convergence through a four-point correlation
function or a trispectrum in Fourier space. The increase in variance is, at
most, a few percent relative to the Gaussian contribution while the band powers
are also correlated at the few percent level. The non-Gaussian contributions
due to background source clustering is at least an order of magnitude smaller
than those resulting from non-Gaussian aspects of the large scale structure due
to the non-linear evolution of gravitational perturbations. We suggest that the
background source clustering is unlikely to affect the precision measurements
of cosmology from upcoming weak lensing surveys.
