The distribution and spatial dispersion patterns of citrus, Phyllocnistis citrella Stainton, leafminer eggs and larvae were assessed in an experimental lime orchard in Dade County, Florida. Significantly higher egg and larval densities were found on apical leaves on young branches compared with older, middle, and bottom leaves on young branches. The spatial dispersion pattern determined for larvae generally were aggregated on 48−70% of the sampling dates. No significant differences in egg densities were observed among the top, middle, or lower tree canopy. However, egg and larval stages were considered statistically aggregated (b > 1) within the canopy. Sample size requirements for fixed levels of precision were determined for eggs and larvae using estimated variance-mean relationships obtained from the Taylor power law regressions. The performance of the sampling plan was evaluated using resampling software. When egg densities fluctuated between 0.34 and 0.58 eggs per leaf, the performance of the sampling plan required too few samples. Performance of existing sampling plans for larvae was low when larval densities fluctuated between 0.12 and 0.16 larvae per leaf, but improved for higher densities ≥1.97 larvae per leaf. Mean samples sizes for a precision level of 0.25 were 10 leaves per tree.
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Peña et al. (1997) studied this question.