The Airplane in Forest-Pest Control 



is learning more and more about how 

 to do the job with better trees. 



RUSSELL B. CLAPPER is an associate 

 pathologist in the Bureau of Plant In- 

 dustry, Soils, and Agricultural Engi- 

 neering. Since 1925 he has been mak- 

 ing all types of crosses between the 

 Oriental chestnuts, the American 

 chestnut, and native chinquapins to 

 determine the resistance of the new 

 hybrids to the blight and to find out 



how various other characters are in- 

 herited. 



JOHN M. MILLER, a senior ento- 

 mologist, conducts research and control 

 investigations in the Forest Insect Divi- 

 sion, Bureau of Entomology and Plant 

 Quarantine. He has been with the De- 

 partment of Agriculture since 1910. 

 Since 1945 he has been conducting 

 studies dealing with the resistance of 

 new pine hybrids at the Institute of 

 Forest Genetics, near Placerville, Calif. 



THE AIRPLANE IN FOREST-PEST CONTROL 



J. S. YUILL, C. B. EATON 



The airplane has become a new 

 weapon in the never-ending battle 

 against destructive forest insects. As in 

 military operations, it is bringing about 

 radical changes in strategy. Aircraft 

 are serving two purposes in this phase 

 of forest protection : For detection sur- 

 veys to locate serious insect outbreaks 

 and for the application of insecticides 

 to control dangerous infestations. 



The extent to which those opera- 

 tions can be carried on from the ground 

 is seriously limited because the areas 

 involved are often large and remote, 

 and because the cost of ground opera- 

 tions in forests is high, even under the 

 most favorable conditions. Many out- 

 breaks of insects in the past conse- 

 quently have had to be allowed to run 

 their natural course until eventually 

 they were checked by exhaustion of 

 the food supply, changes in weather 

 conditions, increase in the abundance 

 of natural enemies, or other factors. 

 But, in contrast to ground equipment, 

 airplanes can cover large and isolated 

 areas quickly and in most cases at a 

 reasonable cost. Although improve- 

 ments must be made in equipment and 

 procedures to develop aerial methods 

 for extensive general use, the progress 

 since the Second World War has been 

 encouraging. 



Finding the enemy, estimating the 

 numbers, and determining the rate of 



movement are as essential in combat- 

 ing insect outbreaks as in conducting 

 a successful military campaign. The 

 Bureau of Entomology and Plant 

 Quarantine, in cooperation with vari- 

 ous Federal, State, and private agen- 

 cies, carries on extensive surveys each 

 year to obtain such information for 

 planning control operations. The work 

 commonly includes cruising represent- 

 ative sample plots; reconnaissance in- 

 spections by truck, horseback, or foot; 

 and visual examination from moun- 

 taintops or other vantage points. Ob- 

 viously, the surveys are limited by the 

 relatively small proportion of total 

 forested area that can be covered in a 

 season. In the search for better and 

 faster methods, the idea was advanced 

 that if the observer could use a moving 

 observation point an airplane in- 

 stead of a mountaintop he could cover 

 much more territory in a day. 



THE FIRST AIR SURVEYS of defoliat- 

 ing insects were conducted in Canada 

 in 1922 and 1923. In a week, air-borne 

 observers mapped several thousand 

 square miles seriously defoliated by the 

 spruce budworm; by ground methods, 

 that work would have taken 3 to 4 

 months. In following years, limited air 

 surveys were made in both Eastern 

 and Western States to detect and map 

 several other insect outbreaks. The 



