SOCIAL WASPS AND HORNTAILS 



75 



immediately in front of the spot, of the great black 

 antennal scape, which would certainly render useless for 

 direct vision any eyes situated immediately behind it. 

 Yellow streaks bound more or less of the outline of the 

 eyes, and greatly improve the appearance. 



On the top of the head we see three small, polished, 

 glassy-looking knobs, frequently of a ruby or yellow 

 colour, and arranged in triangular form. These are the 

 ocelli, or simple eyes, and their number and arrangement 

 are both very characteristic of the order Hymenoptera. 

 We find the same little organs in bees, appearing like 

 tiny sparkling gems, half hidden by the hairs amongst 

 which they are imbedded. In the ichneumon-flies, saw- 

 flies, &c., we find a similar arrangement. 



These are all the parts that are visible from above in 

 the natural position of the organs ; to get at the rest of 

 the complex apparatus of the head we must open the 

 jaws, and then underneath we are introduced to a be- 

 wildering collection of organs, as- puzzling at first sight 

 as a piece of modern machinery. But a little turning 

 and twisting about, and examination from various points 

 of view, soon enables us 

 to make out the general 

 plan and to see the rela- 

 tion of the parts to one 

 another. 



First, and just under- 

 neath the position occu- 

 pied by the mandibles 

 when closed, are two thin 

 blade-like pieces beset with 

 hairs pointing forward 

 (Fig. 26). These are the terminal portions of the max- 

 illae, or secondary jaws, which, as well as the mandibles, 



Ttl 



FIG. 2.6. Labium and maxillae of 

 Wasp : I, labium ; m, maxillae ; Ip, 

 labial palpi ; mp, maxillary palpi ; 

 p, paraglossae. 



