ANTS AND WASPS 63 



running from its attachment to the thorax to the 

 middle of the outermost or rounded edge of the wing 

 (Fig. 23), the lower and more flexible part being bent 



FIG. 23. Wing of Wasp, showing line of folding. 



under the rest, so that the wing becomes only half as 

 broad as before. 



In consequence of this peculiarity, the name Dip- 

 loptera, or "doubled-wings," is given to that section of 

 the order which contains all the wasps, and by this 

 peculiarity they may at once be distinguished from all 

 other Hymenoptera. One would naturally suppose that 

 there must be some connection between this curious 

 habit and the economy of the insects something to 

 account for so strange a departure from the general 

 practice of the order; but if there be, it has yet to 

 be discovered. 



Our British wasps are of two totally distinct kinds. 

 Those that usually obtrude themselves upon our notice 

 are the social wasps of the family Vespidce, and, like 

 the ants and other social insects, they exhibit the 

 peculiarities of the three so-called sexes, the common 

 abode, and the common labour for the common welfare. 

 But besides these, there are the solitary wasps of the 

 family Eumenidce. which, from their habit of burrow- 

 ing in sandy banks, are often called Sand Wasps and 

 Mason Wasps. These have but two sexes, do riot form 

 large communities, and, after having provisioned their 

 nest with food sufficient to last the whole lifetime of 



