254 INSECT TRANSFORMATIONS. 



grass and everything green, as if the turf had been 

 pared off from the surface, the only plant untouched 

 being the tiny bird-tare {Ornithopus perpusillus). \ 

 On digging here to learn the cause, we found these 

 larvae already full fed, and about to pass into pupae, 

 after having left nothing upon which they could sub- 

 sist. It was not a little remarkable that they seemed 

 to be altogether confined to this spot ; for we did not 

 meet with a single foot of turf destroyed by them in 

 any other part of the heath, or in the adjacent fields. 

 So very complete, however, was their destruction of . 

 the roots on the spot in question, that even now, at 1 

 the distance of two years, it is still visibly thinner of J 

 herbage than the parts around it.* 



Rt^aumur gives a similar account of their ravages 

 in Poitou, where, in certain seasons, the grass of the 

 low moist meadows has been so parched up in conse- 

 quence, as not to afford sufficient provender for the 

 cattle. He describes the soil in Poitou as a black 

 peat mould ; and it was the same in which we found 

 them at Blackheath, with this difference, that the spot 

 was elevated and dry. According to M. Reaumer, 

 also, their only food is this sort of black mould, and 

 not the roots of grass and herbage, which he thinks 

 are only loosened by their burrowing.f This view 

 of the matter appears strongly corroborated by the 

 fact that several species of the family feed upon the 

 mould in the holes of decaying trees, particularly the 

 larva of a very beautiful one (^Ctenophora Jiaveolatay 

 Meigen), which is very rare in Britain. It is proper 

 to mention, however, that Mr. Stickney's experi- 

 ments,! contrary to the conclusions of Reaumer, 

 indicate that these larvae devour the roots of grass ; 

 and Stewart says they " feed on the roots of plants. 



J. R. f Reaumer, v. 12, &c. 



1 Obs. oil Hip Grub. 



