246 



COLLEGE ZOOLOGY 



The hind- or metathoracic legs possess 

 three very remarkable structures, the pollen 

 basket, the pollen packer, and the pollen 

 combs. The pollen basket consists of a con- 

 cavity in the outer surface of the tibia with 

 rows of curved bristles along the edges. By 

 storing pollen in this basketlike structure, it 

 is possible for the bee to spend more time in 

 the field, and to carry a larger load on each 

 trip. On the inner edge of the distal end of 

 the tibia is a row of stout bristles, the 

 pecten. Opposing the distal end of the tibia 

 is the proximal end of the metatarsus bear- 

 ing a plate or lip, the auricle. The auricle 

 glides over the outer surface of the pecten 

 and presses against the oblique outer sur- 

 face of the end of the tibia when the joint 

 between these structures is flexed backward. 

 The auricle and the pecten, working to- 

 gether, constitute the pollen packer, since 

 their manipulations force the sticky pollen 

 masses into the pollen basket. In loading the 

 pollen baskets, the pollen brushes of the 



mesothoracic pair of legs collect pollen from 

 the brushes of the front legs and from other 

 parts of the body, and are themselves 

 cleaned by being drawn between the pollen 

 combs of the hindlegs. Each pollen comb is 

 then scraped over the pecten of the opposite 

 leg, the sticky pollen being deposited on the 

 outer surface of the pecten or falling on the 

 upper surface of the auricle. The leg is then 

 flexed backward at this joint, the auricle 

 squeezing the pollen outward and upward, 

 and thus packing it into the pollen 

 basket. 



Mouth parts 



The mouth parts of insects are in most 

 cases fitted either for chewing (mandibulate) 

 or sucking (suctorial). The grasshopper 

 possesses typical mandibulate mouth parts 

 (Fig. 145). The mandibles of insects that 

 live on vegetation are adapted for crushing; 

 those of carnivorous species are usually 



Chewing 

 (Orthoptera, Coleoptera) 



W^^ Labrum |a 



Piercing-sucking 

 (Homoptera, Hemipfera) 



Labi 



um 



Maxilla 



Sucking 



(Lepidoptera) 



Mandible 



Figure 145. Some modifications of the fundamental mouth parts in insects. Note the high 

 degree of speciahzation which adapts the animals to different methods of feeding. 



