IN the development and protection of Canadian forests, aircraft have come to play a most important part. The Canadian Surveyor for October in a general account of aviation in Canada explains how aerial photography is used to show the character, distribution, and accessibility of the timber, thus facilitating exploitation on sound lines. Even more valuable is the use of air patrols for noting forest fires, and of air transport in carrying crews and equipment for extinguishing the fires. In Ontario alone during the year 1929 more than three hundred fires were thus detected. Aircraft are also used in combating insect and other pests. These attempts are still in an experimental stage, but the results so far are promising. Areas of fir and spruce affected by spruce bud-worm and of hemlock and balsam affected by hemlock looper have been dusted with calcium arsenate from the air. The method is certainly cheap and fairly thorough. Experiments in Manitoba have shown the effectiveness of dusting wheat with sulphur in order to fight the destructive wheat stem rust. Aircraft are also being used to expose spore traps, in an endeavour to determine the spread of wheat rust and white pine blister rust.