The courtship behavior of whiteflies was examined, focusing particularly on the manner in which males maximized their fertilization rate by optimizing their time expenditure per female. Some males adopted a sneak male strategy in which they approached courting pairs and without preliminary courtship movements attempted copulation. The chief function of this strategy may have been to disrupt other males' courtships. 'Traditional courtship' was described and found to be sequentially invariable. However, if a female performed a maintenance activity during courtship, males had a significantly lower probability of success and had to court for a much longer time to improve their chances. Most males, including naive ones, persisted rather than abandoned these females. Persistence was seen as a strategy by which males could induce females with high sexual response thresholds to mate. Males reduced the primary cost of persistence, a lower encounter rate with other females, by integrating into their courtship strategy the way in which probability of insemination varied with courtship time invested. They neither courted for too short a time nor did they persist past the point of diminishing returns. Females appeared to assess males on the basis of courtship stamina and intensity. Recently mated females would remate only if the male performed a superior courtship in these respects. By copulating with males that performed more vigorous courtships, a female presumably improved the quality of her sperm store. This would increase her reproductive success because the resultant female offspring would receive a superior genetic complement from their haploid father, and the resultant male grandchildren would, on the average, possess the same desirable qualities that made their grandfather successful.