  The Stokeslet and stresslet kernels are commonly used in boundary element
simulations and singularity methods for slow viscous flow. Evaluating the
velocity induced by a collection of Stokeslets and stresslets by direct
summation requires $O(N^2)$ operations, where $N$ is the system size. The
present work develops a treecode algorithm for 3D Stokeslets and stresslets
that reduces the cost to $O(N\log N)$. The particles are divided into a
hierarchy of clusters, and well-separated particle-cluster interactions are
computed by a far-field Cartesian Taylor approximation. The terms in the
approximation are contracted to promote efficient computation. Serial and
parallel results display the treecode performance for several test cases. In
particular the method has relatively simple structure and low memory usage, and
this enhances parallel efficiency for large systems.
