The use of medium and light medium oils and of light medium oils with fluorine throughout the season for the control of codling moth, reduced the CO2 intake of apple leaves. Light mineral oils in lst-brood codling moth sprays involving Pb arsenate and nicotine sulfate or Pb arsenate and Ca arsenate, or Pb arsenate or modified "Dynamite", followed in each case by F 2d-brood sprays, did not have this effect. Light mineral oil and Pb arsenate throughout the season did not significantly lower the CO2 intake. Use of either Pb arsenate or Ca arsenate-"Dynamite" combinations, even when followed by 2d-brood F sprays, reduced the CO2 intake. Modified "Dynamite" sprays were not so serious in their reduction of intake by apple leaves as were the "Dynamite" sprays. Herring oil, 1 pt. per 100 gal., tended to be less injurious to foliage than medium (65-75 viscosity) or light medium (60-65 viscosity) oils at concs. of 1/2-1%. Ca arsenate with mineral oils is less likely to reduce the CO2 intake than Pb arsenate with the same amts. of comparable oils. Ca arsenate with "safeners" such as, ZnSO4 and Ca(OH)2 may be used without materially affecting the CO2 intake of apple leaves. Oils with nicotine sulfate alone resulted in a greater reduction of CO2 intake than when combined with Ca arsenate, Pb arsenate or bentonite.