188 INDIRECT INJURIES CAUSED BY INSECTS. 



tioned a , 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 Sinapis arvensis, from which I 

 have bred Ceutorliynchus contractus (Curculio Marsh) 

 and C. assimilis, small weevils nearly related to each 

 other b . 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 furnips 

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

 of the excrescences into which the bulb shoots, called 

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

 known c . 



* 



We have wandered long enough about the fields to 

 observe the progress of insect devastation; let us now 



a See above, p. 167-168. 



b 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. sulcicottis (C. Pleurostigma, E. B.), which 

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

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

 taken the sexes of R. assimilis in coitu, which do not differ, save that 

 the male has a somewhat shorter rostrum. 



c Spence's Observations on the Disease in Turnips called Fingers 

 and Toes. Hull 1812. 8vo. 



