from one to five per area, depending upon desired attack 

 density. Each attack density was replicated five times in 

 each phloem thickness, resulting in 75 areas. 



The newly infested billets were kept upright at room 

 temperatures of 20 to 27 °C and humidity of 20 to 40 

 percent throughout the experiment, which lasted about 

 4 months. Plastic screen cages were placed ovej the 

 infested areas and stapled to the sapwood. A plastic test 

 tube attached to the base of each cage served to catch 

 emerging beetles. Beetles were collected, counted, and 

 sexed daily. Length of each beetle was measured with an 

 ocular micrometer in a dissecting microscope. After 

 emergence was completed, bark was peeled from each of 

 the 75 areas. Bark areas were measured and the area at 

 the base where entrance holes were made was deleted. In 

 addition, area of phloem injured when the tree was felled 



and thus avoided by beetles was subtracted from bark 

 area. Therefore, the area available to the beetles was less 

 than the approximately 465 cm^ of each delineated bark 

 area. Remaining beetles, length of egg gallery, and suc- 

 cessful attacks (egg gallery starts) were counted. 

 Because egg gallery was not constructed in four areas, 

 analyses were based on the remaining 71 areas. Also, 

 some beetles did not make egg gallery; therefore, num- 

 bers of observations in each attack density differed from 

 the five planned in each phloem thickness. To determine 

 if excessive drying of bark and wood occurred during 

 beetle rearing, thus possibly affecting beetle survival, an 

 increment core about 1 inch long was taken from the 

 center of each area with an increment hammer and 

 placed in a glass vial. Moisture content of the wood then 



Table 1 — Data from study of mountain pine beetle production in ponderosa pine phloem of different 



Attack 



Item 







1 







2 







3 





X 



sd 



n 



X 



sd 



n 



X 



sd 



n 



Brood production (No.) 



1^ 



15.20 



13.63 



9 



26.78 



11.98 



3 



25.47 



16.19 



6 





2 



36.31 



25.64 



7 



34.51 



19.18 



3 



40.28 



19.75 



3 





3 



34.70 



22.85 



9 



56.64 



29.38 



3 



64.57 



32.47 



3 



Percent female 



1 



65.2 



21.54 



9 



62.3 



7.18 



3 



67.0 



14.77 



6 





2 



65.5 



13.06 



7 



81.3 



9.58 



3 



69.5 



9.18 



3 





3 



65.0 



12.98 



9 



69.2 



6.96 



3 



62.2 



17.74 



5 



Female length (mm)^ 



1 



5.34 



.48 



65 



5.25 



.42 



31 



5.45 



.47 



67 





2 



5.81 



.41 



120 



5.66 



.36 



75 



5.47 



.47 



68 





3 



5.77 



.48 



152 



5.82 



.38 



81 



5.72 



.37 



147 



Fifty percent (days)^ 



1A 



92.3 



9.31 



9 



88.7 



19.35 



3 



76.5 



1.87 



6 



beetle emergence 



IB 



19.1 



14.70 



9 



21.3 



13.80 



3 



14.0 



3.58 



6 





2A 



75.0 



5.23 



7 



78.0 



6.00 



3 



75.7 



9.02 



3 





2B 



11.1 



3.02 



7 



, 17.0 



5.57 



3 



15.0 



7.21 



3 





3A 



81.1 



11.10 



9 



76.7 



6.66 



3 



74.4 



5.41 



5 





3B 



23.8 



10.80 



9 



19.7 



2.52 



3 



16.0 



5.24 



5 



Egg gallery (m) 



1 



.48 



.29 



9 



.75 



.25 



3 



.60 



.25 



6 





2 



.48 



.19 



7 



.60 



.14 



3 



.83 



.14 



3 





3 



.49 



.30 



9 



.57 



.15 



3 



.83 



.30 



3 



Phloem thickness (mm) 



1 



1.45 



.28 



9 



1.60 



.26 



3 



1.56 



.28 



6 





2 



2.91 



.28 



7 



2.81 



.54 



3 



2.98 



.51 



3 





3 



3.51 



.44 



9 



3.72 



.13 



3 



3.50 



.23 



5 



Sapwood moisture (pet)'' 



1 



36.7 



11.25 



9 



47.4 



26.17 



3 



32.9 



11.66 



6 



by weight 



2 



45.5 



6.95 



7 



48.5 



7.88 



3 



32.8 



1.55 



3 





3 



36.5 



10.42 



9 



44.4 



9.51 



3 



49.6 



7.17 



5 



^1, 2, and 3 represent thin, medium, and thick phloem, respectively. 



^Female length is measured from front of the head to tip of the elytra. 



is the number of days for 50 percent of the new adults to emerge, starting from the day parent beetles were 

 introduced into a bark area to oviposit. B is the number of days for 50 percent of the new adults to emerge, starting from 

 the day the first new adult emerged from a bark area. 



''Sapwood moisture was determined after beetle emergence was completed. 



2 



