FOREST PROTECTION 



211 



Table 131. — Growth impact by major insects on commercial forest land in the United States and Coastal 



Alaska, 1952 





Impact on growing stock 



Impact on sawtimber 



Insect 



North 



South 



West 



Coastal 

 Alaska 



Total, 

 United 

 States 



and 

 Coastal 

 Alaska 



North 



South 



West 



Coastal 

 Alaska 



Total, 

 United 

 States 



and 

 Coastal 

 Alaska 



Propor- 

 tion of 

 total 

 impact 



Bark beetles: 



Fir beetles _ . 



Mil- 

 lion 

 cu. ft. 



Mil- 

 lion 

 cu. ft. 



Mil- 

 lion 

 cu. ft. 

 537 

 224 

 97 

 7 



53 

 13 



45 



Mil- 

 lion 

 cu. ft. 



. 12' 

 29 



Mil- 

 lion 

 cu. ft. 

 537 

 325 

 103 

 7 



54 



248 

 504 



Mil- 

 lion 

 bd.-ft. 



Mil- 

 lion 

 bd.-ft. 



Mil- 

 lion 

 bd.-ft. 

 3, 148 

 1,238 

 524 

 40 



290 



64 



265 



Mil- 

 lion 

 bd.-ft. 



62^ 

 111 



Mil- 

 lion 

 bd.-ft. 

 3, 148 

 1,672 

 552 

 43 



292 

 1,013 

 1,897 



Percent 

 36. 5 



Pine beetles 





101 



2 



2 



768 

 614 



434 



"119' 

 907 



19. 4 



Spruce beetles 



6 



6. 4 



Other - _ - _ 



. 5 



Defoliators: 



Spruce budworm 



Other 



1 

 190 

 201 



"33' 

 229 



3.4 

 11. 8 



Miscellaneous ' 



22. 







Total, all insects 



398 



363 



976 



41 



1,778 



1, 414 



1, 461 



5, 569 



173 



8, 617 



100.0 



Chiefly hardwood borers, white pine weevil, tip moths, cone and seed insects, spittlebugs, and aphids. 



species of beetles in 1952 were responsible for more 

 than 400 million board-feet of mortality and 

 growth losses in this section. Less spectacular 

 than some of the western epidemics, the ravages 

 of the southern pine, black turpentine, and Ips 

 engraver beetles have nevertheless been substan- 

 tial. Some other important bark beetles are the 

 fir engraver and pine engraver beetles in the West 

 and the eastern spruce beetle in the North. 



Defoliators were second to bark beetles in the 

 amount of damage caused by insects in 1952. 

 They accounted for 17 percent of the impact on 

 growing stock and 15 percent of the impact on 

 sawtimber. 



Defoliating insects reduce the growth of trees 

 by destroying the foliage. Prolonged and severe 

 defoliation of conifers often results in the killing 

 of large numbers of trees. In general, hardwoods 

 can stand more defoliation than conifers, and even 

 several defoliations may not result in substantial 

 tree killing. Thus, 98 percent of the total growth 

 impact on sawtimber from defoliation was loss of 

 growth. 



The defoliators include a few well-known 

 species and a large number of miscellaneous ones. 

 The spruce budworm, widely distributed through 

 the true fir and spruce forests of this country and 

 in Canada, has periodically caused heavy losses. 

 The outbreaks in New England and the Lake 

 States between 1910 and 1926 killed about 14 

 billion board-feet of balsam fir and spruce. In 

 1952, epidemics were in progress in New England, 

 throughout the Rocky Mountain States, and in 

 the Pacific Northwest. The budworm's 1952 

 growth impact is estimated at 54 million cubic 



feet of growing stock, including 292 million board- 

 feet of sawtimber. 



The gypsy moth is an introduced insect that 

 has been a pest in the woodlands of New England 

 for many years. It prefers oaks, and during 

 outbreaks may defoliate hundreds of thousands 

 of acres of oak in a single season. Average 

 expenditures of $1,893,000 a year for the past 20 

 years by the State and Federal Governments have 

 helped to curtail the moth. The total growth 

 impact for 1952 is estimated at only 16.3 million 

 cubic feet of growing stock. 



Tent caterpillars kill very few trees but reduce 

 growth considerably. For 1952, this loss was 

 estimated at 170 million cubic feet of growing 

 stock, including 743 million board-feet of saw- 

 timber. 



Additional important defoliators in 1952 were 

 pine sawflies, larch sawflies, the hemlock looper, 

 and the fir looper. 



Miscellaneous insects are chiefly those listed in 

 the footnote to table 131. Though miscellaneous 

 they are not minor, for they account for 22 

 percent of the growth impact on sawtimber. 



A New Age in Insect Control 



Surveys Are Basic to Detection 

 and Control 



Surveys to appraise the importance and dis- 

 tribution of many forest insects have been made 

 through the years. However, it was not until 

 passage of the Forest Pest Control Act by Congress 



