74 OUR HOUSEHOLD INSECTS 



compound eyes. The jaws themselves are yellow, but 

 the teeth black. Occupying the centre of the head, 

 just above the jaws, is an important and conspicuous 

 organ called the clypeus. It is slightly projecting, and 

 is like a broad plate with an outline which is curved 

 above and angular below. This, too, is bright yellow, 

 but it carries certain black marks upon it, which vary 

 in the different species, but are in most cases sufficiently 

 constant in the same to be used as diagnostic characters. 



Just above the clypeus the two antennae are inserted, 

 not very far apart from each other, in the centre of 

 the heacl. Each consists of a long basal joint, the 

 scape, and a stout, many-jointed, terminal part, the 

 flagellwn. Between the antennae, and stretching from 

 the base of one to that of the other, is a remarkable 

 bright yellow spot of most elegant shape. It usually 

 bears some resemblance to a sort of coronet, and situated 

 as it is, just above the equally brilliant yellow clypeus, 

 it suggests, in conjunction with the latter, the idea of 

 a nobleman's coat-of-arms surmounted by his coronet, 

 as though the wasp were carrying the evidence of its 

 rank and identity on its brow; and it is not a little 

 remarkable that in this coat-of-arms, so to speak viz., 

 the combined clypeus and coronet we really do find 

 some of the best distinguishing marks of the species. 



The sides of the head are occupied by the compound 

 eyes, which, being situated just on the bend, of course 

 command the most extensive horizon possible. They 

 are reniform, or kidney-shaped, there being a deep 

 indentation in their inner outline at that point which is 

 just behind the antennae when they are in their most 

 natural position; and it would almost seem as though 

 this limitation to the extent of the visual organs were 

 in some way or other connected with the presence, 



