Abstract A comparative evaluation of dislodgable and penetrated residues, and persistence patterns of aminocarb and fenitrothion, was made using several formulations containing diluents with different physi‐cochemical characteristics. Spray was applied onto single spruce trees in a tree farm in Shawville, Quebec, using a dosage rate of 90 g AI (active ingredient)/ha for aminocarb and 340 g AI/ha for fenitrothion. Droplet and deposit data were also obtained simultaneously on sampling units. The data indicated that, with both insecticides, low‐volatility diluents provided larger droplets, higher deposits and foliar residues than high‐volatility diluents. The rate of dissipation and persistence patterns of the dislodagable and penetrated residues were also related to the type of diluents used. However, the penetrated residues dissipated slower than the dis‐lodgable residues, indicating their tendency to resist environmental loss by volatilization, photodegradation and leaching by rain. The amounts of dislodgable residues obtained were related to the dosage rate applied, i.e., those of aminocarb were much lower than those of fenitrothion, whereas the penetrated residues were very similar for both insecticides, suggesting a maximum limit beyond which little increase can occur by increasing the dosage rate of application.