64 THE FERTILISATION OF FLOWERS. [PART II. 
which a more or less thick coat of feathery hairs has become 
developed upon the bodies of the females, it has become trans- 
mitted by inheritance to the males also,! so that they in their visits 
to flowers collect pollen as well as the females. It is otherwise 
with the majority of those bees which have acquired the habit of 
not gathering pollen themselves to feed their young, but of laying 
their eggs in the nests of other bees already stored with food. 
Some of these “cuckoo-bees,” which have acquired the habit in 
comparatively recent times, as the parasitic humble-bees (Apathus 
or Psithyrus), have almost the same development of hairs as their 
parent-form ; others which acquired it earlier, as Nomada, Epeolus, 
Fic. 21.—Mouth-parts of a Humble-bee (B. hortorum, 8 ) in retracted condition. 
1.—Head seen from below. 
2 —Head, in side view, with proboscis bent slightly downwards. ant, antenne ; other letters as 
in Fig. 18. 
Celioxys, and Stelis, have almost entirely lost the hairy coat, while 
retaining in perfection the suctorial apparatus which furnishes 
them with their own food. Males and females of these “ cuckoo- 
bees” thus plunder flowers of their honey, like the males of the 
hairy bees, without being of corresponding advantage to the flowers 
in the carriage of pollen ; for only very little pollen adheres to their 
naked or almost naked chitinous bodies.’ 
1 For a further account of this hereditary transmission, see my work No. 613. 
2 | have investigated the actions of male bees and of cuckoo-bees in regard to 
flowers, and embodied my results in my essays, “ Die Entwickelung der Blumenthi- 
tigkeit der Insekten,’’ and ‘‘ Verschiedene Blumenthitigkeit der Mannchen und 
Weibchen” (Kosmos, ix. pp. 8351—870, 415—432, 1882.) 
