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CHAPTER XVI 

 INSECTS AND FLOWERS 



HE nectar of flowers is a favorite food with many insects; 

 all the moths and butterflies, all the bees and many kinds 

 of flies are nectar-drinkers. Flower-pollen, too, is food 

 for other hosts of insects, as well as for many of those 

 which take nectar. The hundreds of bee kinds are the 

 most familiar and conspicuous of the pollen-eaters, but 

 many little beetles and some other obscure small insects feed largely on 

 the rich pollen-grains. But the flowers do not provide nectar and pollen to 

 these hosts of insect guests without demanding and receiving a pa\Tnent 

 which fully requites their apparent hospitality. And several particular 

 things about this pajTnent are of especial interest to us: these are, first, 

 the unusual character of the payment received; second, the great value of 

 it to the plants; and finally, the strange shifts and devices which the plants 

 exhibit for making the pa\-ment certain. 



In the course of this book, so far chiefly devoted to a systematic con- 

 sideration of various kinds of insects and their habits, several interesting 

 ecological relations between plants and insects have been referred to. That 

 plants furnish the nesting-grounds, or "homes," of many insects has been 

 shown: the wood-borers pass their long, immature life concealed and pro- 

 tected in burrows in the bark or wood of trees and bushes; the delicate little 

 leaf-mining caterpillars wind their devious tunnels safely in the soft ti.'isues 

 of even the thinnest of leaves; while in more speciaUzed manner the extraor- 

 dinary gaUs developed on the oaks and roses and other plants serve as safe 

 houses for the soft-bodied Cynipid larvae enclosed by them. The making 

 of homes like these often, indeed usually, serves the double purpose of both 

 housing and feeding the insect; as it gnaws or bites out its protecting bur- 

 row in stem or leaf it is getting the very food it most prefers; as the plant 

 swiftly builds up about the gall-making larva masses of succulent tender 

 tissue, it is supplying in unstinted quantity the very food (plant-sap) which 

 the larva has to ha\e or starve. 



But the food relation may and mostly does exist between plant and insect 

 without combination with the nest or home relation. To the countless hosts 



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