  We present simple formulae for calculating the skewness and kurtosis of the
aperture mass statistic for weak lensing surveys which is insensitive to
masking effects of survey geometry or variable survey depth. The calculation is
the higher order analog of the formula given by Schneider et al (2002) which
has been used to compute the variance of the aperture mass from several lensing
surveys. As our formula requires the three-point shear correlation function, we
also present an efficient tree-based algorithm for measuring it. We show how
our algorithm would scale in computing time and memory usage for future lensing
surveys. Finally, we apply the procedure to our CTIO survey data, originally
described in Jarvis et al (2003). We find that the skewness is positive
(inconsistent with zero) at the 2 sigma level. However, the signal is too noisy
from this data to usefully constrain cosmology.
