4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. IO3 



of the male genital musculature may mean that the external genital 

 organs of male insects, as compared with the mouth parts, are new 

 Structures having no antecedents going far back in hexapod ancestry. 

 The wings are examples of new structures with a highly consistent 

 musculature, but the wing mechanism has been adapted to the thoracic 

 musculature present before wings were developed. 



A study of insect mechanisms, aside from its morphological value, 

 is important from the standpoint of understanding the functional 

 activities of insects, and opens a wide field in entomological research 

 to students who may be mechanically inclined. Insect mechanisms 

 have little resemblance to man-made machines, for one reason, be- 

 cause animals cannot have anatomical wheels, and for another, be- 

 cause the insect cuticle has properties of flexibility and elasticity that 

 react with muscle tension to produce movements that cannot be 

 imitated in the usual rigid materials of human workmanship. The 

 insect machine, therefore, depends on the use of levers and springs 

 and hydraulic apparatus, but still it is not impossible that inventors 

 might get a few hints from its study. 



I. THE HEAD AND THE FEEDING APPARATUS 



The hymenopterous head and the organs of feeding, by comparison 

 with these parts in such orders as Lepidoptera, Diptera, and 

 Hemiptera, show relatively little deviation from the generalized plan 

 of structure in fundamental ways; but, on the other hand, they 

 present numerous minor specializations and many finely adjusted 

 mechanical alterations by which they are adapted to methods of feed- 

 ing and to nonfeeding uses not found in any of the other insects. 

 The structures directly concerned with the intake of food in the bee 

 include the labrum, a large preoral epipharyngeal lobe on the under 

 surface of the clypeus, the mandibles, a maxillo-labial complex, or 

 proboscis, the mouth, and an internal sucking pump. Intimately as- 

 sociated with the ingestive organs, moreover, is a salivary ejection 

 pump, or syringe, for the discharge of the saliva from the salivary 

 duct. The hypopharynx does not appear as an independent organ in 

 the bee ; its distal part is incorporated into the base of the labium 

 and its proximal part forms the floor of the mouth. 



The natural food materials of the bee are principally pollen and 

 nectar, both being carried to the hive for storage, where the nectar is 

 converted into honey. The eating of pollen involves little more than 

 a use of the mandibles in the primitive manner of biting and chewing 

 insects, and modification of the mandibles in the bee pertain chiefly 



