162 THE REPRODUCTIVE ORGANS 



and many of the modifications found in flowers are paral- 

 leled by modifications of the mouth-parts of insects 

 (Fig. 108). The mouth-parts of the simpler insects, e. g. 

 beetles and flies, are so short that they are unable to reach 

 the honey unless it is exposed in an open, shallow flower. 

 Honey in a deep tube is inaccessible to them, and only 

 insects with mouth-parts elongated to form a proboscis are 

 able to reach it. Some flowers have tubes several inches 

 long (8 to 10 inches), and there are insects with probosces 

 long enough to obtain honey from the bottom of them. 



Insect pollinators and their month-parts. Fig. 108 shows 

 the mouth-parts of various insects which visit flowers, 

 i is the head of a beetle (Strangalia attenuata) which can 

 lick honey from shallow flowers ; 2, the head of the Drone 

 Fly (Eristalis arbustorum) with an extensible proboscis ; 

 3, the head of a fly (Rhingia rostrata), in side view ; 4, 

 the proboscis fully extended ; 5, the mouth-parts of the 

 Long-tongued Bee (Anthophora pilipes) ; 6, the end of the 

 proboscis enlarged to show the ' honey-spoon ' ; 7, the 

 Honey Bee (Apis mellifica) with masses of pollen (Po) on 

 the hind legs ; 8, the hind leg of a bee with mass of pollen ; 

 9, collecting-hairs on the leg of a Honey Bee ; 10, a hair 

 magnified, with pollen-grains attached; 11, proboscis of 

 a moth, which is very long and coiled up like a watch- 

 spring. 



Such insects perform unconsciously a valuable service in 

 carrying, on their bodies, pollen from the anther to the 

 stigma, and their habit of visiting flowers for food has 

 probably been an important factor in the evolution of many 

 flowers. On the other hand, the insects have themselves 

 become modified, especially in the organs surrounding the 

 mouth. 



Insects, useful and injurious. In the mature stage, insects are 

 often very useful to flowers, and in many cases seeds can only 

 be developed when insects act as pollinators. It is during this 



