ATHALIA SPINARUM. 311 



frequently four or five being seen on the same 

 leaf. Curtis says that they are preyed upon by 

 swallows. 



Newport remarks that the flies proceed in flights 

 across the fields or district in which they may be 

 located. Thus, he once noticed them very busily 

 ovipositing in a field. On the second day there were 

 scarcely any left on that part of the field where they 

 were first observed ; they were then at work in the 

 middle. By the third day they had proceeded still 

 further, and on the fourth they had reached the 

 opposite end of the field from which they started. It 

 is suggested by Newport that the whole of the eggs 

 are not laid in one day, but may take three or four a 

 very likely supposition considering that each female 

 lays about two hundred and fifty. 



The larva of this Athalia is known to farmers by 

 the name of the " black palmer," " black canker," 

 " black slug," or " nigger." The first published 

 account of its ravages in Britain is contained in a 

 paper by W. Marshall in the ' Transactions of the 

 Royal Society ' for 1783. According to this writer 

 the larva had committed very great ravages in the 

 year before that, and he mentions also that it had been 

 equally injurious in 1760. Yarrell says that it was 

 abundant again in 1818, while from 1833 and onwards 

 it did very great damage. 



There seems to be some reason for believing that 

 the insect may have originally come over from the 

 Continent, for Marshall says that they first made their 

 appearance -on the eastern coast; they were observed 

 to alight in clouds and were found afterwards heaped 

 up on the shore in some places to a depth of two 

 inches. They abound during warm and dry sum- 

 mers ; cold and wet ones checking their spread very 

 effectively. 



Various remedies have been recommended for 

 checking the ravages of the larvae. Spreading quick- 

 lime and the refuse of gas works has been used, and in 



