386 PHILOSOPHICAL TRANSACTIONS. [ANNO 1783. 



troubled, and to assume a whitish or yellowish colour, according to the countries 

 through which they passed. For a long time before the earth shook, the sea 

 appeared considerably agitated, so as to frighten the fishermen from venturing 

 upon it, without any visible winds to make it so. Our volcanos too, as I am 

 confidently assured, emitted no eruptions for a considerable time before ; but 

 there was an eruption of Etna in the first earthquake, and Stromboli showed 

 some fire in the last. 



XI II. Of the Black Canker Caterpillar, which destroys the Turnips in Norfolk. 

 By IV. Marshall, Esq.* Dated Gunton, Norfolk, Aug.11, 1782. p. '217. 



Among the numerous enemies to which turnips are liable, none have proved 

 more fatal here than the black canker, a species of caterpillar, which in some 

 years have been so numerous as to cut off the farmer's hopes in a few days. In 

 other years however the damage has been little, and in others nothing. About 

 20 years ago the whole country was nearly stripped ; and this year it has been 

 subjected to a similar fate. Many thousands of acres, on which a fairer prospect 

 for a crop of turnips has not been seen for many years, have been plowed up ; 

 and as, from the season being now far spent, little profit can be expected from a 

 second sowing ; the loss to the farmers individually will be very considerable, 

 and to the country immense. 



It was observed in the canker-year above-mentioned, that, prior to the ap- 

 pearance of the caterpillars, great numbers of yellow flies were, seen busy among 

 the turnip plants ; and it was then suspected that the canker was the caterpillar 

 state of the yellow fly ; and since that time it has been remarked, that cankers 

 have regularly followed the appearance of these flies. From their more frequently 

 appearing on the sea coast, and from the vast quantities which have at different 

 times been observed on the beach, washed up by the tide, it has been a received 

 opinion among the farmers, that they are not natives of this country, but come 

 across the ocean, and observations this year greatly corroborate the idea. Fisher- 

 men on the eastern coast declare, that they actually saw them arrive in cloud-like 

 flights ; and from the testimony of many, it seems to be an indisputable fact, 

 that they first made their appearance on the eastern coast ; and that, on their 

 first being observed, they lay upon and near the cliffs so thick and so languid, 

 that they might have been collected into heaps, lying, it is said, in some places 

 2 inches thick. Thence they proceeded into the country, and even at the dis- 

 tance of 3 or 4 miles from the coast they were seen in multitudes resembling 

 swarms of bees. About 10 days after the appearance of the flics, the young 

 caterpillars were first observed on the under sides of the leaves of the turnips, 



* The insect here described appears to be the larva of some species of the Linnean genus Tentbredo. 



