INTERDEPENDENCE OF ORGANISMS 19 



hairs, in place of the usual teeth. This is shown in our figure 

 for a pollen-eating soldier beetle (Chauliognathus scutellaris) 

 which swarms upon goldenrod flowers in autumn (fig. 1 1.) 

 Proboscides Most nectar-eating insects have mouthparts 

 prolonged and combined into some sort of a sucking pro- 

 boscis, with which they are better able to reach sequestered 

 nectaries. In general it may be said that the proboscides 

 are of three types: 



1. The hinged and retractile type, variously developed 

 in bees and flies. 



2. The coiled type, characteristic of butterflies and 

 moths. 



3. The jointed and rigid type, characteristic of bugs 

 (Hemiptera) . 



The first of these types is well illustrated by the common 

 honey bee, in which the proboscis is made out of maxillae 

 and labium. Labrum and mandibles are much as in the 

 grasshopper: the labrum is narrower, and the mandibles 

 are not toothed at the tip, but scoop-like, adapting them 



for moulding wax. But the 

 maxillae and the labium are exces- 

 sively elongated, hollowed out in- 

 ternally and closely applied together 

 to form a sucking tube, the anterior 

 part of the alimentary canal being 



FIG. 12. Diagram of head of r . .._ . , . 



honey bee (Apis meiufica, at the same time modified to torm a 



from the side, a, antenna; 



fc.eye; c, labrum; d.mandi- sucking organ and nectar reservoir. 



ble; e, maxilla; r, its cardo; . . - 



s, its stipes and p, its palpus; The resultant prODOSCIS IS Slung 



/, labium, p, its palpus. 



beneath the head upon the car- 

 dines of the maxillae (fig. 12 r), and provided with muscles 

 which readily extend or retract it. At the tip of the stipes 

 is another hinge, which allows the long terminal portion to 

 be folded backward under the head when not in use. This 

 terminal composite joint is hollow, and from its tip pro- 



