Sampling statistics were obtained to develop a sampling protocol for estimating numbers of adult Diaphorina citri Kuwayama (Hemiptera: Psyllidae) in citrus by using two different sampling methods: yellow sticky traps and stem-tap samples. A 4.0-ha block of mature orange trees was stratified into 100.4-ha strata and sampled using each method seven times over a 7-mo period. One sticky trap was deployed per tree on each of 16 trees randomly selected in each stratum, and numbers of adults on the traps were counted 1 wk later. One stem-tap sample in which the number of adults falling into a pan after three rapid taps to a branch was taken per tree on each of 16 trees randomly selected in each stratum. A sampling protocol of one yellow sticky trap on each of 20 trees, or of one stem-tap sample on each of 30 trees, distributed uniformly across an area up to 4.0 ha (excluding block edges) was projected to provide an average sampling precision rate of < or = 25% (SEM/mean x 100) at means of one or more adults per trap or stem-tap sample. Validation sampling indicated 20 sticky trap samples consistently provided the desired precision level at means of approximately two or more adults per trap but not at means of 1.0-1.5 per trap. A sample size of 30 stem-tap samples consistently provided the desired average precision level, but the precision of some individual estimates was > 25% at means of around one adult per tap sample.