Areas of lighter budworra defoliation extended west of Excursion Inlet 

 to the west side of Glacier Bay and south along the northwest portion 

 of Chichagof Island, Many of the latter areas were heavily defoliated 

 in 1954 and top kill of hemlock is common. 



Very noticeable budworm defoliation occurred on mountain and western 

 hemlock in the Endicott River area and on spruce near the headwaters 

 of the Skagway River. Both areas of defoliation were near timberline 

 where moderate defoliation has been observed to do little damage. 



The total area of generally moderate-to-heavy defoliation, within which 

 some top killing of hemlock can be expected, covers approximately 620,000 

 gross acres. The remaining 2,1 million acres within the boundaries of 

 the old outbreak contained black-headed budworm populations capable of 

 only light defoliation, and thiis in the stands near timberline. Since 

 heavier defoliation at timberline has been observed to cause little 

 damage and no top killing to either western or mountain hemlock, the 

 areas pi*esently defoliated can be expected to make quick recovery. 



Scattered light epidemic pockets of the black-headed budworm were found 

 on Ball, Suemez, Baker and Heceta Islands west of Prince of Wales Island, 

 and in the vicinity of Ketchikan at Ward Cove, Mud Bay and other nearby 

 locations. The epidemic pockets on the islands were on the ocean side 

 and were more or less widely separated from each other. No pockets are 

 extensive in size and no serious defoliation of hemlock was observed. 



Prior to 1955 it was thought that the black-headed budworm was not 

 causing complete tree kill but only top kill, which in some stands was 

 destroying a fair portion of tree length, especially in the largest 

 trees. Observations made this year at Thayer Lake on Admiralty Island, 

 and Orchard Lake on Revillagigedo Island, show that the initial 

 assiMption was not correct and that the budworm is capable of killing 

 entire trees. Just what percent of the trees in heavily defoliated 

 stands has been killed is yet to be determined, but initial estimates 

 are placed at ten percent. In terms of volume the percentage of budworm 

 kill will be higher. Furthermore, conditions have been observed which 

 strongly suggest that hemlock, which was heavily defoliated, may continue 

 to lose growth and eventually die. This condition was also noted at 

 Thayer Lake and Orchard Lake and has been mentioned by other field 

 personnel. 



It must be pointed out that this hemlock kill and volume loss con- 

 stitutes only a very small portion of the total timber supply, but in 

 certain restricted areas could influence the cutting schediile. 



Trend 



The cold, wet summer and fall retarded black-headed budworm development 

 to such an extent that hemlock twig sampling had to be delayed. As in 

 previous years, trend of the outbreak is determined from budworm egg 

 concentrations found on fixed hemlock twig samples. Defoliation can be 

 expected to be serious when egg counts of 0,11 eggs per twig-inch of 

 needles are reached. Results of the 1955 twig sampling are presented in 

 table 2, 



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