46 THE FERTILISATION OF FLOWERS. [PART II. 
Bracon), Chalcididse (Pteromalus), and Ruby-tails (Chrysis), many 
species, of the Wasps (Diploptera) and Sand-wasps (Fossores), 
almost all which I have had the opportunity of observing, and 
- of the bees all species without exception, rely almost exclusively 
on a floral diet. 
All these groups, excepting the last two, are only capable of 
sucking honey from flat exposed surfaces, and even among the 
Sand-wasps there are few species whose proboscis can reach some 
millimetres into a tubular flower; so that a large proportion of 
flowers are exempt from the visits of all Hymenoptera except bees. 
But bees, which not only feed when in the perfect state exclusively 
on the produce of flowers, but nourish their young thereon also, 
are in such intimate and lifelong relations with flowers, that they 
show more adaptations for a floral diet, and are more important for 
the fertilisation of our flowers, and have therefore led to more 
adaptive modifications in these flowers, than all the foregoing orders 
put together. A closer study of bees is therefore essential for 
a right. understanding of the fertilisation of many of our flowers. 
The Family of Bees. 
The various structural modifications in bees will be most easily 
understood, if we arrange them in the natural order of genetic 
descent. For the grounds of my views, I must refer the reader 
to a special essay of mine on the subject of bees.? If my conclusions 
are correct, bees are descended from certain Sand-wasps, which, 
like the species at present existing, pursued spiders, insects 
and their larvae, disabled them with their sting, carried them 
to their nests, and laid an egg beside each, thus supplying the 
resulting larva with living food,—while the perfect insects fed 
entirely on honey and pollen; these were the founders of the new 
race, who gave up the old manner of feeding the young to feed 
them with a portion of their own food, disgorged from their 
stomachs. The race thus started differed at first from the others 
in nothing but this habit; but in the course of time, filling 
an unoccupied place in the economy of nature, they increased 
1 For a discussion of the genealogical relations of the families of Hymenoptera and 
their gradual acquirement of proficiency in anthophilous habits, consult my recent 
works, “ Wie hat der Honighiene ihre geistige Befihigung erlang ?” (Hichstddter Bienen- 
zeitung, 1875, 1876 ; and note in Nature, vol. xv. p. 178) and ‘* Die Entwickelung der 
Blumenthiitigkeit der Insekten,” ti. and iii. 
2 Anwendung der Darwin'schen. Lehre auf Bienen,” Verh. der naturh. Ver. fiir 
pr. Rhein, u. Westfal, 1872, pp. 1-96. 
Pines! RS ae 
