A stratified sampling procedure was devised to investigate the spatial patterns of the predominant mosquito species in Louisiana rice fields. Prior to harvest, highly significant differences (P <0.01) in the density of Psorophora columbiae larvae existed among strata within the field. Over 93% of the Ps. columbiae larvae collected were obtained within 1 m of the contour levees. Following harvest, no significant differences (P > 0.05) were detected in the numbers of Ps. columbiae larvae collected among strata. Spatial patterns of Anopheles crucians larvae were independent of harvest and the larvae were equally distributed among all strata, regardless of collection date.