292 Insects most injurious to Cultivators : — 



stem withered ; the pupa (c) being seen in the ^^^ 



centre of the stem ; at d, two of the flies are 



shown, which are drawn considerably smaller 



than in the original figure. Fig. 103. is the 



same fly magnified ; and in ^g. 101. / and ^• 



show the larva ; f, the natural size ; and g, 



magnified. 



Mr. Markwick planted some of the dis- 

 eased roots under] a hand-glass^ where they 

 flourished very much, and threw out strong 

 shoots on each side ; the middle shoot withering. On pulling it 

 up subsequently, an empty chrysalis was found in each stem. 

 On the 14th of May, several flies were produced from some other 

 plants, which had been enclosed in gauze; 6 plants producing 

 6 flies. After the larva had changed to a pupa, the mischief 

 ceased ; the root not being so materially injured as to prevent its 

 throwing out fresh lateral shoots, or stocking itself, as the farmers 

 term it. In short, Mr. Markwick adds, " At harvest time, I was 

 most agreeably surprised to find a good crop of wheat, and the 

 ears large and fine, throughout the whole field." It was con- 

 sidered the best crop on his farm ; and he supposed it would 

 yield about three quarters and a half of threshed corn from each 

 acre. It was erroneously suggested, that this might possibly be 

 the American Hessian fly (Cecidomyia destructor Say; see Maga- 

 zine of Natural History^ vol. i. p. 228.) ; but, if even this had been 

 the case, Mr. Markwick observes that a little good English hus- 

 bandry, by keeping the ground in heart, and thus enabling the 

 wounded shoots to repair themselves by strong lateral ones, would 

 prevent our being alarmed to a great degree. He adds various 

 conjectures relative to the introduction of the eggs into the field ; 

 considering it improbable that it was by means of the manure, 

 which consisted entirely of lime. It was only the wheat which 

 was sown early (about the end of September or beginning of Oc- 

 tober) that was attacked ; which, it was conjectured, was caused 

 by the cold, at the approach of winter, destroying the fly before 

 the late-sown wheat had sprung out of the ground. In one field, 

 where a part of it was sown with white, and the other with red, 

 wheat, at the same time, the white wheat was much affected, and 

 the red but very little. A figure of the under side of the insect 

 (which, from the figures, appears to be twice as large as Mr. 

 Raddon's) is added; from which it seems that the under side of 

 the body is pale, with two large black spots on the mesosternum. 

 In No. 91 of the Annals of Agriculture, the history of the same 

 fly is given by the late Arthur Young, accompanied by notes 

 from Sir Joseph Banks, who determined it to be identical with 

 the Musca pumilionis. 



Pvlr. Marsham also published some additional observations 



