34 



INTRODUCTION TO EVOLUTION 



labrum 

 mandible 



mnnrlihip X'} 



labrum 



2ncl maxilla 

 1st maxilla 



abrum 

 mandible 



1st maxil 

 palps 

 galea 



2ncl max 



(labium 



hypopharynx 

 palps 



GRASSHOPPER 



BEE 



FIG. 3.8. Mouth parts of grasshopper and honeybee. Upper sketches show mouth parts 

 in place in the head, lateral view. Lower sketches show mouth parts removed, front view. 



but is improvised by bringing together the pair of 1st maxillae and the 

 labial palps. The plunger within the tube is a tonguelike structure formed 

 from a portion of the labium. A muscular sac at the upper end of the tube 

 acts in sucking up liquids much as does the rubber bulb of a medicine 

 dropper (pipette). 



Butterflies and moths also have a tube through which nectar from flow- 

 ers is drawn into the mouth (Fig. 3.9). As in bees, suction is produced by a 

 muscular sac connected to the tube; there is, however, no plunger 

 (tongue) in the tube. In many butterflies and moths the tube is long and 

 slender and when not in use is coiled like a tiny watchspring under the 

 animal's head. This slender tube is composed of the pair of 1st maxillae 



