REPRODUCTION AND DISPERSAL 



841 



bee (Apis) and the bumblebee {Bombus) are the most efficient of all 

 pollinating insects, because of their remarkable and continued activity 

 from the opening to the close of the flowering season, because of their 

 precision, which insures the successive and rapid pollination of many 

 individuals of the same species, and because they visit flowers for pollen 

 as well as for nectar. Their hairy legs are well suited for carrying pollen, 

 and their long probosces enable them to secure nectar in partially closed 

 or tubular flowers (figs. 1166-1169). Among the flowers that are almost 

 entirely dependent upon bees for polhnation are those with irregular 

 {zygomorphic) corollas, as in the legumes, the violets, and many of the 

 mints; in certain instances (as in the clovers and aconites) the natural 

 distribution area is confined to those parts of the world frequented by 

 bees. The bees are diurnal insects and visit only diurnal flowers, and 

 it commonly is thought that they have a high color sense and a keen sense 

 of smell which aid them in detecting the presence of flowers. The wasps 

 are of minor importance as pol- 

 linating insects, though some 

 flowers are pollinated chiefly by 

 them (as in the figwort). 



Moths and butterflies. — The 

 butterflies and certain moths 

 (classed in the Lepidoptera) are 

 nectar-feeders, and they possess 

 greatly elongated and special- 

 ized mouth parts, known as 

 maxillary laminae. The butter- 

 flies, like the bees, are diurnal 

 insects and are able to get nectar 

 from deeply hidden parts of the 

 flower ; as a rule, they visit 

 showy and fragrant flowers (such 



as various honeysuckles and pinks). Most remarkable, perhaps, are the 

 hawk moths (Sphingidae) , a group consisting chiefly of nocturnal insects 

 with maxillary laminae of great length (up to 80 mm.), which are coiled 

 when not in use (fig. 1170)^ The nocturnal hawk moths visit flowers 

 rapidly and with the precision of bees, thus contrasting with the more lan- 

 guid and haphazard movements of the butterflies; they are attracted espe- 

 cially to heavily scented white nocturnal flowers with long corolla tubes 

 (e.g. Nicotiana alata, which becomes fragrant as it opens in the dark). 



Fig. 1 1 70. — A hawk moth {Phlegethonius 

 sexta) visiting the flower of Petunia; note the 

 long corolla tube of the flower and the long 

 mouth parts of the insect. — After Folsom. 



