activity are available from the early days of European settlement of North 
America. For example, writings of the Moravians, a religious group which 
emigrated from Austria and Czechoslovakia to the upper Piedmont region of 
North Carolina, mentioned extensive dying of pines near the settlement of 
Hope in 1796. In recent years, this area has suffered from periodic outbreaks 
of southern pine beetle, Dendroctonus frontalis, and it is likely that these 
early writings refered to a bark beetle outbreak (Price and Doggett, 1978). 
Timely, accurate data on status and trend of outbreaks and magnitude of 
losses is required to plan and conduct action programs designed to reduce 
losses. These data are difficult to obtain and often not readily available. 
Surveys using aerial photography are an effective means of acquiring this 
information. 
Review of the Literature 
Effectiveness of aerial photography for imaging trees killed by bark beetles 
was demonstrated over 25 years ago when Wear and Bongberg (1951) identified 
trees infested by the western pine beetle, D. brevicomis, on black and white 
panchromatic film in eastern Oregon and California. Several years later 
Heller et al. (1959) demonstrated that color aerial film was superior to 
panchromatic film with a red filter (A-25) for detection of trees killed by 
southern pine beetle in western North Carolina. Several photo scales were 
evaluated and a scale of 1:7,920 was shown to be the best compromise of 
accuracy and cost. 
During the mid 1960's great interest developed in both agriculture and 
forestry in use of color IR film for detection of plants stressed by disease 
or insect infestation. Several workers reported success in early detection 
of insect- or disease-caused stress in agricultural plants with color IR 
film. In some cases sufficient enhancement to detect "previsual" symptoms 
was reported (Norman and Fritz 1965, Hart and Meyers 1968, Colwell 1964). 
Attempts to detect conifers infested by bark beetles before foliage discolor- 
ation occurs has established rather conclusively that color IR film is not 
effective for this purpose (Ciesla et al. 1967, Heller 1971). 
Color IR film has certain advantages over color film for mapping or recording 
trees killed by bark beetles, in spite of its inability to detect trees prior 
to visible foliage discoloration. When used in combination with a Wratten-12 
(minus blue) filter, color IR film is capable of penetrating atmospheric 
haze. In addition, it is capable of separating conifers from deciduous 
hardwoods, with conifers imaging in darker shades of brown or red-brown and 
hardwoods imaging brilliant red. Color IR film is of value where rapid type 
mapping of coniferous forests is desired. Double sampling with color IR 
photography was used operationally in the southeastern United States for 
estimating levels of southern pine beetle infestation for several years 
(Ciesla 1969). Characteristics of color and color IR film as they relate to 
imaging of forest insect damage were recently summarized (Ciesla 1977). Both 
films seem to be equally effective in imaging bark beetle damage, and numerous 
examples of their effective use appear in the literature (Wear et al. 1964, 
Ciesla et al. 1967, Wert and Roettgering 1968, McGregor et al. 1974, Klein 
1973). Film choice is, therefore, a matter of personal preference or need to 
satisfy secondary objectives, such as ability to penetrate haze or distinguish 
coniferous and deciduous hardwood forest. 
     
    
     
   
  
    
    
   
    
    
    
    
  
   
    
  
  
   
    
    
     
  
  
    
   
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