INSECT ENEMIES OF EASTERN FOREST 
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FIGURE 63.—Adult bark beetles: A, The southern pine beetle; B, one of the turpen- 
tine beetles similar in shape but larger. (In both insects note the end of the 
abdomen rounded out in a convex Manner. C, and D, ends of abdomens of /ps 
spp. Showing end concave and armed with toothlike projections. 
5 or more generations occur each season, the exact number being de- 
pendent on the length of the summer season and on weather condi- 
tions. Under optimum conditions it is not unusual to obtain a 10- 
fold increase in a single generation. With 5 generations a year, the 
application of elementary arithmetic will explain the sudden out- 
breaks and extremely rapid increases known to take place. 
