130 COMPETITION AND CONSTANCY. 



driven off, though many species were in bloom in the adjacent beds. Three 

 other individuals worked solely on Zinnia, though the same bed contained 

 7 other species in bloom, while a bumble-bee visited exclusively 28 heads 

 of Tragopogon in a 10-minute period, in spite of the competition of 10 

 other kinds of flowers. 



Bennett's studies of constancy. — Bennett (1874, 1884:175) was 

 apparently the first to make an extensive study of the visits made by an 

 insect in one journey from the hive, in the hope of confirming or confuting 

 Aristotle's statement. The 66 observations made concerned only the butter- 

 flies, the syrphids, and apids, and they appeared to indicate very different 

 degrees of constancy. On the whole, the butterflies manifested but a small 

 degree of fidelity; they preferred yellow or pink flowers and showed a 

 marked tendency to adhere to one of these colors after starting with 

 it. In the case of Eristalis, it exhibited little constancy in two instances, 

 while in two others it confined its visits to a single though different flower. 

 On the other hand, four observations of Syrphus gave only one case of 

 constancy. 



Of 33 observations made on various species of Bombus, 4 showed visits to 



3 distinct species, while in 6 others the number of species noted while the 

 insect was in sight was 2. In 23 instances the bumble-bee visited but a 

 single species while under observation, but these were of the most diverse 

 kinds and colors. It was quite obvious that at the same spot different bees of 

 the same species were visiting different kinds of flowers. Pollen masses 

 were examined. in two cases and found to consist wholly of the pollen of the 

 flower on which the bee was taken. The honey-bee was constant to one 

 species for 5 out of 6 observations, the exception consisting of 1 visit to 

 Scabiosa and 9 successive ones to Centaurea. It was concluded that the 

 butterflies exhibit little constancy, the flies greater constancy, while this 

 is much greater for the bumble-bees and all but absolute in the honey-bee. 

 Constancy appeared to increase in proportion to the part performed by the 

 insects in carrying pollen from flower to flower. 



Christy's studies of methodic habits.— Christy (1884:186) adopted 

 Bennett's methods and corroborated his general results. The honey-bee 

 was found to be perfectly methodic, not one individual changing from one 

 species of flower to another, even in mixed groups. Among the bumble- 

 bees one individual was seen to visit no less than 5 different species, 3 visited 



4 species, 4 went to 3 species, 18 to 2 species, and 29 were constant to a 

 single species. The Lepidoptera were found to be much more constant 

 than in Bennett's observations, only 3 of the 12 individuals going to a 

 second species. It was observed that bees were less constant in early 

 spring and autumn, probably because fewer flowers were out, a honey-bee 

 in spring going twice from Anemone to Ranunculus. Bumble-bees proved 

 more methodic when visiting blue flowers than those of other colors, though 

 the results were not regarded as conclusive. 



Mueller's results.— Mueller (1876) reached the same conclusions as 

 Darwin with reference to the causes of constancy. With respect to the 

 differences in the behavior of male and female bees (1881), he found that 



