i8 



GENERAL BIOLOGY 



Since insects visit flowers for food, naturally, it is the parts 

 of their bodies that serve for collecting and carrying the 

 nectar or pollen that are most modified for flower visitation. 

 It is their feeding apparatus, therefore, that most merits our 

 present attention. The nature of the remarkable changes 

 that have fitted insect mouthparts for nectar-gathering will 

 best be understood after comparison with the simple biting 

 mouthparts of a grasshopper. These are shown in fig. n. 

 The upper lip or labrum is a simple transverse membranous 

 flap covering the mouth above. The lower lip or labium is 

 a compound, appendage-bearing flap covering the mouth 

 below. Between the two are two pairs of jaws that swing in 

 and out laterally, and that are toothed on their opposed tips; 

 but one of each pair is shown in the figure. The upper pair 

 (mandibles) lie directly beneath the labrum ; each mandible 

 is simple and strongly toothed. The lower pair (maxillae) 

 lie directly below the mandibles, between them and the 

 labium. Each maxilla consists of two basal pieces (cardo 

 and stipes) and three terminal appendages; the innermost, 

 the lacinia, is simple, and toothed internally; the next, the 

 gale a, is two jointed and closely fits over the back of the 

 lacinia; and the third, the palpus, is five jointed and is 

 sensitive at its tip. The labium is a compound organ made 

 of a pair of appendages similar to the maxillae, fused to- 

 gether during their development on the middle line. The 

 fused cardines constitute the submentum, the fused stipites, 

 the mentum, and the three terminal parts are easily recog- 

 nizable, although the lacinia is greatly reduced in size, the 

 galea greatly expanded, and the palpus but three jointed. 



Of insects with this simple type of mouthparts, only a few, 

 chiefly beetles, have taken to flower visiting; and these 

 show more or less of narrowing of the front of the head, 

 adapting it for entering corollas, and alteration of the tip of 

 the lacinia to brushes of stiff pollen-, or nectar-gathering 



