has been going on in Alaska for many years but has progressed at a much 

 more rapid rate since 1952 when the first forest entomologist was 

 permanently assigned to the Region. 



Field collections of forest insects are made both by entomologists of 

 the Research Center and by cooperators throughout Alaska. Insects 

 collected by cooperators are submitted to the Research Center for rear- 

 ing and identification. Many specimens are in turn forwarded to the 

 National Museum and elsewhere for specific determination by specialists, 



An insect reference collection is maintained in Juneau which primarily 

 includes insect specimens found associated with forest damage and with 

 damage to forest products. Examples of insect-caused damage are also 

 included in this collection. A considerable amount of useful informa- 

 tion concerning the distribution, hosts, type of damage, and the 

 biology and habits of the various insects is gained through collection 

 records and the rearing of insects. 



Plans for 1958 include emphasis on field collections and will involve 

 some type of systematic field sampling. An expansion of laboratory 

 rearing facilities is also planned. 



Large Hemlock Volume Loss Caused by Insect Defoliators 



The 1948 through 1955 epidemics of the black-headed budworm and the 

 hemlock sawfly resulted in permanent damage to western hemlock in many 

 areas of Southeast Alaska. During 1956 and 1957 aerial and ground 

 surveys were made to determine the acreage involved and the volume loss 

 sustained as a result of these epidemics. 



From aerial mapping surveys it has been estimated that 112,000 acres of 

 hemlock timber suffered light to heavy tree-killing and top-killing. 

 This figure does not include light scattered top-killing which extends 

 over a large area. The 112,000 acres comprise 8,000 acres of heavy 

 loss, 52,000 of moderate loss, and 52,000 of light loss. Losses are 

 most prominent on Admiralty Island, the east side of Prince of Wales 

 Island, the north end of Revillagigedo Island, Mitkof Island, and 

 Lindenberg Peninsula. 



To determine volume loss, ground surveys were made in four areas: one 

 a heavy loss area at Thayer Lake on Admiralty Island; the other three 

 in predominately moderate loss areas at Cholmondeley Sound and 

 Exchange Cove on Prince of Wales Island and at Cow Creek on Revilla- 

 gigedo Island. From these surveys it is estimated that heavy loss is 

 7,250 board feet per acre, moderate loss 2,700 board feet per acre, 

 and light loss 1,350 board feet per acre. These are net volume losses; 

 the volume of cull material, estimated at 34 percent, having been sub- 

 tracted. 



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