Table 1.— Characteristics of the Scotch pine plantation and N. sertifer egg populations in the 



four blocks sampled. 



Item 







Block 







A 



A 



r> 





T\ 

 JJ 



A 1 1 



All 



Mean tree dbh (inches) 



0.9 



1.6 



2.4 



1.4 





Mean height of dominants (feet ) 



5.8 



8.6 



7.9 



8.0 





Trees per acre 



644.5 



1,482.4 



999.0 



1,192.4 





Eggs per tree 



638 



867 



1,504 



1,203 





Eggs per square foot 



9 



29 



34 



34 





Eggs per acre 



411,000 



1,285,000 



1,521,000 



1,435,000 





Mean number of eggs per cluster 



50.3(3 ) a 



71.8(6) 



55.2(10) 



58.6(9) 



59.3(28) 



Standard error 



12.6 



21.3 



7.4 



10.3 



6.3 



a Sample size in parenthesis. 



Table 2.— Number and relative density of N. sertifer egg clusters 

 according to vertical position in the tree crown canopy. 



Item 





Height Above Ground (ft) 





6-9 



3-6 



0-3 



All 



Mean number of eggs per cluster 



72.6(5) a 



59.0(16) 



50.6(7) 



59.3(28) 



Standard error 



26.5 



61.2 



11.4 



6.3 



Proportion of egg clusters in the 

 sample 



.18 



.57 



.25 



1.00 



Current foliage space in the 

 sample - ft 3 



7 



34 



59 



100 



Egg clusters per cubic foot of foli- 

 age space (no.) 



.71 



.47 



.12 



.28 



a Sample size in parenthesis. 



clusters were distributed in the upper, middle, 

 and lower thirds of the tree height in the ratio of 

 1:2:1. When the number of clusters is compared 

 with the amount of space occupied by current 

 foliage (where the eggs are deposited) in each 

 height level, it is apparent that the density of 

 clusters increases from 0.12 per cubic foot of 

 foliage space in the lower crown to 0.71 per cubic 

 foot in the upper crown. This substantiates the 

 conclusion of Lyons (1964), that the sawfly pre- 

 ferred to oviposit on the exposed portions of the 

 crown. 



These examples show the wide range of data 

 that can be obtained with our vertical sampling 

 pole. We feel that it is widely applicable to the 

 investigation of other problems. 



ACKNOWLEDGMENTS 



The field assistance of David L. Hubbard, 

 forestry technician, and Alan A. Squires, 

 biological technician, is greatly appreciated. 



LITERATURE CITED 



Lyons, L. A. 



1964. The spatial distribution of two pine sawflies and 

 methods of sampling for the study of population 

 dynamics. Can. Entomol. 96:1373-1407. 

 Wilson, L. F. and D. J. Gerrard. 



1971. A new procedure for rapidly estimating Euro- 

 pean pine sawfly (Hymenoptera:Diprionidae) popula- 

 tion levels in young pine plantations. Can. Entomol. 

 103:1315-1322. 



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