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An atmospheric tracer experiment using SF6 was designed to assess changes in the dispersive environment in the trunk space of a southern pine forest through four thinning regimes. The experimental plot was thinned from dense boles and thick understory (>140 ft2 (13 m2) basal area) in four stages with the final basal area being 70 ft2 (6.5 m2 ). Observations indicate that thinned stands are less susceptible to bark beetle attack and one possible reason could be that the plumes of pheromone the insects use for signaling cannot achieve the intended purpose in the thinned stand. The pheromone mechanism could be altered through direct dilution of the gaseous plume, through a reduction in spatial coherence of a plume making it more difficult to follow back to a source or through loss of the plume vertically from the stand environment through lofting due to surface heating and loss of overhead containment. This work is part of a larger program to improve the success of forest insect management strategies using pheromone. Data analysis is on-going but the high frequency tracer plumes examined in this study show that the plumes are more dilute and much less coherent spatially in the thinned stands. The plumes are filamentous in nature in all cases but wander (whip) across a larger volume of space in the thinned stands.