C 242 ) 



XXIII. Obfervations on the InfeSls that infejicd the Corn in the Tear 1795. 

 In a Letter to the Rev, Samuel GooJenough, LL. D. F. R, S. 7r. L. S. 

 By Thomas Mar/I:am, Efq. Sec. L. S. 



Read May 3, 1796. 



Dear Sir, 



TOWARDS the end of July laft, a friend of mine (Mr. Long) 

 who had the management of a farm in Hertford fliire, was 

 telling me that an infe6l had made its appearance among the 

 wheat, which threatened to do much mifchief; that it was found, 

 in many inftances, to have attacked one, two, or more grains in an 

 car; and that it was difcoverable by thofe grains appearing yellow,. 

 or as it were ripe, while all the remaining grains in the fame ear 

 were perfe6lly green. — I defired that gentleman to bring me up 

 I'ome of the difeafed ears, which he did ; and I found them exactly 

 as he had defcribed them. — On opening thofe grains that feemed 

 difeafed, I found in many of them an orange-coloured powder, and 

 in fevera!, one or two very minute /arv^e, differing in colour, from a 

 ycllowiih white to a deep yellow. They were too minute for exa- 

 mination by the naked eye ; but by applying a deep magnifier I 

 {^erceived them to be the larvae of a fmall mufca, and to refemble very 

 much thofe aphidivorous larvix that produce one particular family 

 of the mufcce. They were thick at one end, and gradually dimi 

 rifhed to a point at the other, where the head was fituate. They 

 extended and contrafted themfelves at pleafure ; to which was 



added 



