Natural History 535 



tissues of the adult. From the pupa case the adult insect emerges, 

 different in form and habit, winged and aerial. Metamorphosis 

 implies far more than the acquisition of wings, and one of the 

 most marked differences between larva and adult is in most cases 

 the difference in the food and the method of taking it. This is 

 so great that the transition from larval to adult habits could not 

 take place along with continuous external activity the quiescent 

 period of reconstruction is essential. 



8 



Insects and Man 



A great many insects live their busy days and perish without 

 affecting man at all, except that they delight him with their ex- 

 quisite colours and markings and interest him with their ways, but 

 some are his friends, and perhaps more he reckons his foes. Even 

 the Bee he too often shrinks from, remembering the weapon she 

 carries and forgetting her honey and the infinite service she 

 renders by securing the pollination of many flowers. The 

 Termite may be as much a tiller of the soil as the Earthworm is, 

 but she attacks his furniture and the wood of his house; the 

 cochineal and "lac" that insects provide are relatively insignifi- 

 cant; and "locusts and honey" may be thought a dainty dish in 

 the East, but a locust swarm will blight every green thing in a 

 district. "He scatters the seed, and when he looks for green heads 

 to appear, the earth opens, and, lo, an army of long-faced, yellow 

 grasshoppers come forth!" 



Locusts 



Wherever locusts are resident they do a great deal of 

 damage, but it is their sudden migratory swarms which are so 

 disastrous. They increase in numbers during favourable seasons; 

 then, one year, when the food-supply is insufficient, they collect 

 in immense swarms and travel long distances, devouring every 

 green thing in their path. A tobacco-grower saw a swarm of 



