148 INTRODUCTION 
the hind-legs are thickly covered with hair from the tibia to the coxa. Even the 
metathorax is sometimes provided with two well-developed tufts of hair, under which 
considerable quantities of pollen can be accumulated (H. Miiller, ‘Fertilisation,’ p. 51). 
Compared with the species of Sphecodes, those of Halictus and Anthrena have an 
advantage in that their basal tarsal joints are considerably broader, and the tarsal 
brushes are consequently more effective. ‘These bees will therefore use exclusively 
or chiefly as larval food the pollen that is collected by the hairy covering of the hind- 
legs, whilst for the species of Sphecodes this method of collection is subsidiary. 
N 
/\e Xf 
Nol) \ 
| y Vy 4 
AW WY 
>> 2 
aes —= 
= 
YT 
—= 
Fic. 60. Halictus and Anthrena (after Hermann Miller). 
quadricinctus 2 9: wm, mentum (chin); 7/#, ligula (tongue); a, paraglossae (accessory tongues); i, 
labial palp. (2) Right hind-leg of the same bee. (3) Metathorax and right hind-leg of Anthrena ovina 
&Kilg. 9; 2x, right tuft of hair onthe metathorax. Other references in (2) and (3) as in Fig. 58. (4) Single 
hairs from the body of an Anthrena ovina AZg. 9, captured upon a flowering willow. To the feathery 
branches of these hairs numerous pollen-grains are sticking. 
(1) Labium (lower lip) of Halictus 
As in all the three above-named genera the entire body is hairy, it follows that 
the bees in visiting numerous flowers cover themselves with pollen, which they 
subsequently remove with the tarsal brushes, so that the quantity heaped up on the 
special collecting-hairs is considerably augmented, especially as the hairs are mostly 
feathery. In Sphecodes the hair-covering of the body is very scanty. Only the 
legs are well covered, especially the outer sides of the posterior tibiae. The brushes 
on the inner side of the basal tarsal joints are somewhat better developed than in the 
genus Prosopis, a bee which is at the lowest stage of adaptation. The species of 
the latter have an almost naked body, and the small basal tarsal joints possess but 
a feebly-developed covering of hair. Pollen, however, often clings to these bees, 
