PENTSTEMON GLABER. 



67 



While the first part of table 48 contains the actual record of visits, the 

 exact significance of these can be obtained only by reducing them to the 

 same basis as to length of observation and number of flowers. This reveals 

 a variation of five times in the total number of visits per hour. More 

 suggestive, however, is the balance between Pseudomasaris and Osmia; 

 the decrease of the one with the increase of the other indicates the effect 

 of competition for the same species, either actually in progress or wrought 

 out in the seasonal behavior. 



Observations 1 and 2 in table 49 give the lists of visitors from 10 to 

 10 h 40 m on two mornings a week apart with 50 flowers concerned in each 

 case. There were 19 flowers in number 3, which was made on June 27 

 from ll h 20 m to 12 a. m. Observation 4 was taken on July 10 from 9 h 47 m 

 to 10 h 26 m on 20 flowers. 50 flowers were used for 5, which was on July 12 

 from 10 to ll h 30 m a. m. Number 6 was made July 18 from 10 h 4 m to 

 ll h 40 m and 50 flowers were in the group under observation. As usual, 

 the first number in each column indicates the visitors, the second the 

 visits made. 



Table 49. — Visitors and visits to normal flowers. 



Species. 



Observation. 



Osmia phaceliae 



bruneri 



Pseudomasaris vespoides 



Clisodon terminalis 



Melissodes fremonti 



Andrena vicina 



Prosopis varifrons 



elliptica 



Apis mellifica 



Bombus juxtus 



Halictus pulzenus 



Thanaos martialis 



Total 



26:65 

 2:2 

 6:18 

 6:25 

 2:4 

 2:3 

 2:2 

 2:2 

 1:2 

 1:32 

 0:0 

 0:0 



17:20 

 0:0 

 3:4 

 3:9 

 0:0 



2:2 

 2:2 

 1:1 



0:0 



4:9 



8:51 



0:0 



0:0 



0:0 



1:1 



0:0 



0:0 



2:2 



0:0 



0:0 



0:0 



1:8 



5:113 



0:0 



0:0 



0:0 



1:1 



0:0 



2:2 



1:1 



1:1 



0:0 



0:0 

 27:71 

 4:17 

 6:25 

 2:2 

 0:0 

 2:2 

 0:0 

 1:2 

 1:30 

 0:0 

 0:0 



15:63 



11:126 



43:149 



0:0 

 17:20 

 4:4 

 1:8 

 0:0 

 1:5 

 0:0 

 0:0 

 0:0 

 4:4 

 0:0 

 0:0 



27:41 



COMPARATIVE VALUES. 



Osmia phaceliae 



bruneri 



Pseudomasaris vespoid 

 Clisodon terminalis . . . 

 Bombus juxtus 



Total 



39:87 

 3:3 

 9:27 

 9:37 

 1:48 



25:30 

 0:0 

 4:6 

 4:13 



0:0 

 18:40 

 36:225 



0:0 



9:0 



75:233 



45:64 



66:282 



0:0 



4:36 



22:510 



0:0 



4:4 



48:570 



0:0 

 18:47 

 3:12 

 4:17 

 1:20 



30:103 



0:0 

 25:40 



2:16 



The reduction in the number of visitors and the great decrease in the 

 visits made by them shown by the second observation were due entirely 

 to the wind, the other factors being essentially the same. A similar decrease 



