RAVAGES OF CATERPILLARS. 219 



extraordinary number could not have failed to at- 

 tract public notice on other shores. The nature of 

 these insects is to lie in the pupa state during the 

 winter under ground; and when, at its appointed 

 time, the fly comes forth, it only lives to lay its eggs, 

 usually dying within a few days or weeks. It must 

 have been, therefore, after the laying their eggs on the 

 turnips, and not before, that clouds of the flies were 

 seen at sea and on the shore, though not arriving, 

 but going away. They were, doubtless, impelled by 

 that restless desire of change felt by all animals 

 when death is approaching, and which in tropcal 

 countries is yearly exemplified in the destruction of 

 locusts, for these always make for the sea, and 

 perish there. But though they were thus got rid 

 of in August, 1782, they left a progeny behind them 

 in the black caterpillars which were hatched from 

 their eggs. In the summer of 1783, accordingly, 

 we are told by Mr Marshall, that whole districts 

 were ravaged by them, the descendants, of course, 

 in the second generation, of the saw-flies which pe- 

 rished .on the beach and at sea the preceding au- 

 tumn. 



Some caterpillars, which either conceal them- 

 selves under ground, or feed on roots and the wood 

 -of trees, do considerable injury, without apparent 

 cause; and often give occasion to the popular notions 

 respecting mysterious blights. In this manner will 

 the caterpillars of the ghost moth (Hepialus Humuli) 

 gnaw the roots of the burdock, and, what is of more 

 consequence, of the hop plant, till the shoots are 

 weakened and the leaves droop in bright sunshine. 

 We have repeatedly seen, in the gardens about Lee, 

 a large branch of the red-currant bush, though pre- 

 viously healthy and loaded with fruit, all of a sud- 

 den droop and wither, giving good cause to sur- 

 mise, except in the leaves not being brown or 



