The caged mosquito bioassay places the test insects in a mesh cage in the path of an insecticidal space spray to investigate the effect of a machine or chemical type on mosquito mortality. The effects of different mesh densities on mosquito confinement and mortality were investigated. In addition, the predominant pathway for exposure of a caged mosquito bioassay was established. The number of weaves per unit area was the primary parameter for mosquito confinement. Mortality increased with a reduction in mesh density but not with any of the measurable mesh characteristics. There was no correlation between mortality and the wire gauge, the opening size, or the percent openness. It is hypothesized that open area is the predominant parameter and that where the openness is similar, the effects of wire diameter on collection efficiency can be seen. The predominant exposure mechanism was a space spray. The residual tarsal contact had a significant effect on mosquito mortality only after 24 h of exposure. The combined effect of space spray and residual tarsal contact shows a significant increase in mortality after 30 min compared to space spray alone.