CATERPILLARS. 383 



a narrow bay or inlet ; and if they had, we ought to have 

 heard of their departure as well as their arrival, since their 

 extraordinary number could not have failed to attract 

 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 rest- 

 less desire of change felt by all animals when death is 

 approaching, and which in tropical 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 perished on the beach and at sea the 

 preceding autumn. 



Some caterpillars, which either conceal themselves under 

 ground, or feed on roots and the wood of trees, do consider- 

 able injury, without apparent cause ; and often give occa- 

 sion 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 red-currant bush, though previously healthy and 

 loaded with fruit, all of a sudden droop and wither, giving 

 good cause to surmise, except in the leaves not being brown 

 or parched, that it had been struck with lightning. On 

 cutting into such branches, however, the cause was 

 uniformly found to be the ravages of the caterpillar of the 

 currant hawk-moth (^JEgeria ttpuliformis, Stephens), which 

 abounds in the vicinity. But we have also remarked that 



