46 NORMAL AND EXPERIMENTAL POLLINATION. 



It followed the same route each time among the flowers. The capacity to 

 visit many flowers in succession varies in the different species. B. juxtus 

 visited an average of 36 flowers in succession, while proximus came to an 

 average of 17. One individual of juxtus visited 116 flowers in one circuit, 

 and other individuals went respectively to 95, 62, and 52 flowers. 



The queen of Bombus proximus lands and takes nectar, but it is so large 

 that the under tip of the abdomen rubs the style branches and in that way 

 leaves pollen on them. Much of the pollination is done, however, when the 

 stamens are shaken. This queen goes from flower to flower for nectar 

 without making any effort to get pollen. The drone of this species poises 

 in the air and then lands on the stamens; it takes no nectar, but collects 

 pollen alone. It scrapes this off with the second pair of legs and from these 

 on to the third pair, where a heavy load of pollen soon accumulates. When 

 poised in the air in front of the flowers, it is scraping pollen from the sides of 

 its abdomen and putting it in the corbiculae. It works very nervously 

 and rapidly at each flower, but flies deliberately from one to another. 



Bombus bifarius, upon landing at a flower, takes a position in which the 

 tip of the abdomen is between the style and the petals. It comes for nectar 

 only and seldom touches the recurved styles because of the position of the 

 abdomen. Apis mellifica lands below and then has to crawl to the opening 

 of the nectary. It comes for both pollen and nectar, depending upon its 

 needs at the time. Megachile pugnata, although a much less frequent visitor 

 to these flowers, is a very effective pollinator. Its fewer visits are doubtless 

 due to the fact that this species is not so common in this locality. The 

 abdominal brushes are large and yellow and consist of unusually long, stiff 

 bristles. It lands in the proper place for sucking nectar and straddles the 

 style. This places the mouth-parts directly above the opening to the necta- 

 ries. It pushes out its proboscis and sucks nectar, while the hind legs move 

 rapidly and scrape pollen on to the abdominal brushes. Halictus (Lasioglos- 

 sum) sp. hangs on to the anthers with its front legs in some flowers, but 

 usually twists its abdomen around the base of the filaments while sucking 

 nectar. This places it in a position to have pollen fall on it, and as the bee 

 flies away, pollen is jarred loose and falls on the stigmatic surface of the 

 flower. The brushes on the legs collect pollen as when it hangs on the 

 stamens. Vespa germanica stands on the petals, reaches in to the nectary, 

 and sucks nectar. While sipping, Andrena madronitens elevates the tip 

 of its abdomen in such a way that the scopa rubs the style branches in some 

 flowers and the anthers in others. This makes it a very effective pollinator 

 and one that uses the scopa in a different manner from other bees. There 

 are also long blue-green pollen loads on its legs. Argynnis atlantis comes 

 for nectar, the tip of its abdomen rubbing the recurved stigmas as it works. 



The normal visitors to Chamaenerium are given in tables 31 to 33. In 

 the first case, 120 flowers on 20 racemes were observed for 30 minutes, in 

 the second 80 flowers on 12 racemes for an hour, and in the third 140 flowers 

 on 25 racemes for two successive hour periods. 



For an hour period the number of visitors varied from 28 to 4, and the 

 number of visits from 158 to 728, the average number of visits per insect 

 ranging from 6 to 50. Bombus contributed 45 of the total of 60 visitors, 

 and these made 1,391 of the 1,424 visits. A calendar of the normal visitors 



