30 



NORMAL AND EXPERIMENTAL POLLINATION. 



covered, though it hovered low over 3 others. Bombus occidentalis went to 

 7 normal flowers and hovered over 2 of the changed ones, while for B. juxtus 

 the numbers were 8 and 1 respectively. 



ARTIFICIAL AND PAINTED FLOWERS. 

 Crepe-paper corollas. — In all the flowers employed the anthers were 

 just beginning to dehisce, as flowers at this stage had been found to be most 

 attractive to insects. Other open flowers nearby were removed, so that 

 they would not attract visitors from the group under observation. After 

 the petals and sepals were removed, artificial corollas of red, blue, yellow, 

 or white crepe-paper were wired below the anthers. A normal flower 

 was left for comparison near each artificial one, 3 flowers of each color 

 being used in the experiment, making a total of 15 for each of the two lands. 

 Table 11 shows the response to them, as well as the color preferences. 



Table 11. — Visits to natural and paper flowers. 



Species. 



Normal. 



Red. 



Green. 1 White. 



Bombus juxtus 



morrisoni. . . , 

 Andrena vicina 



crataegi 



prunorum . . , 

 Acmaeops longicornis . 



Osmia bruneri 



phaceliae 



Prosopis wootoni 



varifrons . . . 



basalis 



Pipiza sp 



Diptera 



100 



7 



25 



2 



1 



17 



18 



1 



14 



10 



2 



1 



Total . 



4:31 



The visits to normal flowers were six times as many as to the artificial 

 ones. While the bees clearly avoided the imitations as a whole, there 

 was a great difference in response to the various colors. The visits to green, 

 white, and red were negligible. 



Artificial corollas similar to those used in the previous experiment were 

 made of crepe-paper, but with the petals fringed by cutting them length- 

 wise. Four artificial flowers of each color and 16 normal flowers were used. 

 Observations from 8 to 10 a.m. on the first morning and from 8 to 9 a.m. 

 on the second gave the results shown in table 12. 



Of 222 visits, only 18 were made to the artificial flowers, chiefly by Bombus 

 and Osmia, a fly being the only other visitor to them. It is significant 

 that Apis did not go to a single imitation. While the numbers are too 

 small to be of much value, it is interesting to note that blue and yellow 

 were again the preferred colors. 



Painted corollas. — When the petals were painted blue, green, or yellow 

 with water-colors, Bombus juxtus visited as many painted as normal flowers, 

 in contrast to the ratio of 11:1 for natural and paper flowers. Andrena 

 crataegi went only to the blue flowers, in addition to the normal ones. 



