A correlogram showing weak spatial covariance structure in counts of Western Corn Rootworm (WCR) / corn stalk. An exponential  model has been fit to the lag estimates to permit extrapolation to origin.  If reliable this model would suggest that only about 20 % of the variability in WCR counts has a spatial component.  The fact that the relationship is negative suggests that the relationship is one of repulsion, which is not surprising at the high densities we experienced (mean ~ 12 / stalk).

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updated:  20 September 2000