INSECTS IN RELATION TO PLANTS 



227 



B Among mandibulate insects, beetles and caterpillars that eat the 

 oral envelopes show no special modifications for this purpose; pollen- 

 feeding beetles, however, usually have the mouth parts densely clothecl 

 with hairs, as in Euphoria (Fig. 265). In suctorial insects, the mouth 

 parts are frequently formed with reference to floral structure; this is 

 the case in many butterflies and particularly in Sphingidae, in which the 

 length of the tongue bears a direct relation to the depth of the nectary 

 in the flowers that they visit. According to Miiller, the mouth parts of 

 Syrphidse, Stratyomyiidae and Muscidae are specially adapted for feed- 



FIG. 265. A, right mandible; B, right maxilla; C, hypo- FIG. 266. Pollen-gath- 



pharynx, of a pollen-eating beetle, Euphoria in da. Enlarged. ering hair from a worker 

 (The mandibles are remarkable in being two-lobed.) honey bee, with a pollen 



grain attached. Greatly 

 magnified. 



ing on pollen. In Apidae, the tongue as compared with that of other 

 Hymenoptera, is exceptionally long, enabling the insect to reach deep 

 into a flower, and is exquisitely specialized (Fig. 129) for lapping up 

 and sucking in nectar. 



Pollen-gathering flies and bees collect pollen in the hairs of the body 

 or the legs; these hairs, especially dense and often twisted or branched 

 (Figs. 266, 91) to hold the pollen, do not occur on other than pollen- 

 gathering species of insects. Caudell found that out of 200 species of 

 Hymenoptera only 23 species had branched hairs and that these species 

 belonged without exception to the pollen-gathering group Anthophila, 

 no representative of which was found without such hairs. Similar 



