188 INDIRECT INJURIES CAUSED BY INSECTS. 



tioned *, called by Mr. Walford the wire-worm, have 

 been discovered in October just below the leaves in a 

 single bulb of this plant. — The small knob or tubercle 

 often observable on these roots is inhabited by a grub, 

 which, from its resemblance to one found in similar 

 knobs on the roots of Shiapis arve77sis, from which I 

 have bred Ceutorhynchus contractus [Curculio Marsh) 

 and C assimilis, small weevils nearly related to each 

 other ^. This, however, does not seem to affect their 

 growth. Great mischief is occasionally done to the 

 young plants by the wire-worm. I was shown a field 

 last summer in which they had destroyed one- fourth of 

 the crop, and the gentleman who showed them to me 

 calculated that his loss by them would be 100/. One 

 year he sowed a field thrice with turnips, which were 

 twice wholly, and the third time in great part, cut off 

 by this insect. — Whether the disease to which turnips 

 are subject, in some parts of the kingdom, from the form 

 of the excrescences into v/hich the bulb shoots, called 

 fingers and toes, be occasioned by insects, is not certainly 

 known *. 



We have wandered long enough about the fields to 

 observe the progress of insect devastation ; let us now 



" Sec above, p. 167-168. , 



*> Swamm. ii. 81. col. b, — Gyllenhal in describing the last-named 

 species, so common on the flowers of siliquose plants {Insecta Sue- 

 cica, iii. 142.), asks if his R. sulcicoUis {C. Pleurostigma, E. B.), whicii 

 agrees with it in most respects, except in having toothed thighs, be 

 not the otlicr sex ? This query I can solve in the negative, having 

 taken the sexes of li. assuiiUis in coitu, which do not differ, save that 

 the male has a somewhat shorter rostrum. 



* Spence's Observations on the Disease in Tiirnijis called Fingers 

 and Toes. Hull 1812. 8vo. 



