HYMENOPTERABEES 



159 



When the honey-bees and humble-bees, the complex suctorial apparatus of 

 which, in its various activities, has just been described after Hermann IMiiller's 

 account, are declared by this investigator to be the most important of all insects 

 in the pollination of our native flowers, his assertion, of course, only applies to those 

 individuals concerned in the care of the young, i. e. the workers among honey-bees, 

 and the females and workers among the humble-bees. 



In all bees which provide for their own young, the males, H. Muller goes on 

 to say, are of much less use in pollinating plants than the females, as they only look 

 after their own maintenance^ and consequently neither collect pollen, nor visit 

 flowers very diligently. Yet, in all species in which a more or less thick coat 

 of feathery hairs has become developed upon the bodies of the females, this is also 

 present in the males, so that they, since they visit flowers, transfer pollen as well 

 as the female. It is othenvise with most of those bees which have acquired the 

 habit of laying their eggs in the nests of other bees already stored with larval food, 

 instead of nourishing their brood on flower-food they have themselves collected. 



ant 



Fig. 6t). Mouth-parts oj a huvthle-bee {Rombns hortoriim, L., 5), retracted (after Herm. Muller). 

 (i) Head seen from below. (2) The same seen from the side (with proboscis directed somewhat down- 

 wards), ant, antennae. Other references as in Fig. 64. 



Some of these ' cuckoo-bees ' (Apathus, or Psithyrus) have almost the same develop- 

 ment of hairs as their parent-stock (Bombus), from which H. Muller concludes that 

 they acquired the habit of brood-parasitism in comparatively recent times. Others 

 again, in v/hich the transition to this mode of life took place very long ago (Coelioxys, 

 Epeolus, Nomada, Stelis), have in the course of time almost completely lost the coat 

 of hairs that was useful to their ancestors but would be useless to them. They retain 

 in full perfection, however, the ancestral suctorial apparatus, of which they make 

 constant use in procuring their own food. Males and females of these ' cuckoo-bees ' 

 thus plunder flowers of their nectar, like the males of hairy bees, without being 

 of corresponding advantage to the flowers in the transfer of pollen, for only very little 

 of this adheres to their naked or almost naked chitinous investment. 



To the admirable account that Hermann Muller has given of the structure and 

 functions of the mouth-parts of bees, a few observations remain to be added 

 regarding the actual length of the proboscis in various species, and the visits made 

 to flowers by the members of various groups. It is obvious that there must be 

 an intimate connection between the length of the proboscis of insects and the 



