THE EVOLUTION OF THE BEE. 67 



inheritance and adaptation caused the various forms and 

 colours of the grubs to be produced. The flies under the 

 influence of the same causes have also varied, and the result 

 is that the insects are as numerous in their species as all the 

 vertebrates put together. The tree shows the chief modifi- 

 cations which I shall follow as regards those branches leading 

 to the Bees. 



From the Biting Flies, which by a side branch give rise 

 to the Orthoptera (such as the Grasshopper) and Coleoptera 

 (Beetles), two changes are noticed. The mouth is modified so 

 as to produce the Stinging Flies, and the wings are so altered 

 that two separate orders of Stinging Flies exist, viz., the Two- 

 winged (Diptera) and the Half- winged Flies (Hemiptera). 



By another branch variation we get the Gauze Wings 

 (XeiLvoptera), which divide into the Licking Flies with 

 membranous wings (Hymenoptera), and the Sipping Flies 

 with scaled wings (Lepidoptera). The Licking Flies again 

 vary into two branches, one of which throws off the Ruby 

 Flies, Ichneumon Flies, Saw Flies and Ants ; the other pro- 

 bably gave rise to Bee-like Flies, forms which though not now 

 existing, must have preceded Bees. We have now come to 

 variations which depend more upon external appearance, 

 minute structural differences and habits of life; and these 

 would take a far greater time to name than I have to spare, 

 I must content myself with naming the few forms we are to 

 discuss to-night. 



The Bee-like Flies must be supposed to have given rise 

 to true Bees and to Wasps. The true Bees vary in their 

 hairyness, as well as in their mouth organs and other parts. 

 Some are without hair either on every part or on special parts 

 of their bodies, and others vary more in the colour of the hair 

 and in the shape of the body than in any important detail. 

 The points which differentiate the Bees from each other must 

 be left unnoticed. I content myself with having traced the 

 insect through its evolution as far as such evolution is known. 

 It will no doubt be found that some of the branches of this 

 tree are out of place when more light has been thrown on 

 evolution; but any such change will not interfere with the 

 general outlines or with the correctness of the leading deduc- 

 tions from the known facts. 



