AN ECONOMIC ENTOMOLOGY. 



the delicate sensory structure on the inner surface. An antenna 

 is moniliform, or bead-hke, when the joints are more or less 

 spherical and set together in such a way as to resemble a series 

 of beads on a string. 



As a rule, the antennae are straight, without break from base 

 to tip ; but occasionally they are geniculate, or elbowed ; that is to 



say, there is one very long 

 basal joint, the "scape," fol- 

 lowed by a series of smaller 



Fig. io. 



V\G 



J 1/ I / Head of wasp, to show regions: a, 



'^^ y .^Ct^ ^C^' compound eyes ; b, clypeus ; c, la- 



Antennal types: a, moniliform ; (^Joints ciliated; brum; rf, mandibles; ^, ocelli ; y, place 



c, bristle-tufted ; rf, plumose ; ^.setaceous. where antennae are inserted. 



segments set in at right angles to it. Usually an elbowed an- 

 tenna is also clubbed at the tip, and so we divide the structure 

 into "a scape" at the base, the "club" at the tip, and the 

 " funicle" embracing the intervening portion. 



The feelers may be clothed with fine, soft, more or less dense 

 hair, and are Xh&n pubescent ; or furnished with lateral hairs of 

 moderate length set in regularly, and are then ciliated or fringed ; 

 or they may have single or bunches of stiff bristly hair, and are 

 then said to be bristled, or bristle tufted. 



These are all the movable appendages of the head, and there 

 remain only the organs of sight, which are perhaps better con- 

 sidered under the heading of sense organs. It is only necessary 

 to say here that the compound eyes are often very prominently 

 developed, and that they are usually set at the sides, often form- 

 ing the greater portion of the head itself The ocelli, on the 

 other hand, are always very small structures ; in the adults, never 

 more than three in number, and (juite variably arranged. 



