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 
1 for other hosts of insects, as well as for many of those 
I 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 payment 
which fully requites their apparent hospitality. And several particular 
things about this payment 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 payment 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 tissues 
of even the thinnest of leaves; while in more specialized manner the extraor¬ 
dinary galls 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 have 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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