HYMENOPTERA—BEES 159 
When the honey-bees and humble-bees, the complex suctorial apparatus of 
which, in its various activities, has just been described after Hermann Miiller’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. Miiller 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 otherwise 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, 
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PRN Ail! wy 
Fic. 69. Mouth-parts of a humble-bee (Bombus hortorum, L., 3), retracted (after Herm. Miller). 
(1) Head seen from below. (2) The same seen from the side (with proboscis directed somewhat down- 
wards). anf, 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. Miiller concludes that 
they acquired the habit of brood-parasitism in comparativély recent times. Others 
again, in which 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 Miiller 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 
