affecting the Pea-crops, Mangold-vmrzel, and Beet. 407 



economy of the insects affecting the various crops of France, 

 that M. Bazin had sent him many larvae of Silpha opaca, which 

 were more elongated than in the other known species : they were 

 shining-black, with a little yellow at the anterior margins 

 of the segments ; they were found in great numbers in some 

 red-beet fields, and were accused of devouring the leaves of this 

 useful plant, and thus causing great ravages in the plantations 

 when the plants began to sprout. M. Guerin saw them eat the 

 leaves of the red-beet which he gave them, as caterpillars would 

 have done. M. Bazin and his son had detected these larvae in 

 their fields in great numbers, mounted upon the leaves of the 

 plants and eating them. 



The distance from Londonderry being so considerable, the 

 larvae transmitted by post did not reach me alive ; and conse- 

 quently I never had a chance of rearing the beetles to identify 

 them. M. Guerin has been more fortunate, for at the begin- 

 ning of July he saw a larva change to a pupa ; the middle of the 

 same month many buried themselves three or four inches in the 

 earth, making a little oval cavity by kneading the soft earth with 

 their head, aided by pressure exercised by the back, &c. On 

 the 14th he saw a white pupa ; and on the 24th the Silpha 

 hatched. It remained two days white in the earth, gradually 

 becoming brown, and eventually black, when it came forth. 

 Some of Mr. Maxwell's larvae also changed to greyish-white 

 pupae, about three inches below the surface of the soil, but he 

 did not obtain the beetles from them. 



It is quite possible that these larvae may be the offspring of 

 different species of the genus Silpha, yet I am disposed to think 

 the French and Irish are the same, supported as this supposition 

 is by their similar economy. I observed some of the larvae were 

 longer and narrower than others, which may be m.erely a sexual 

 variation. It is not that they assume the broader form before 

 being transformed into pupae, for many of the small and young 

 ones were equally short and broad in proportion. I think the 

 one found at the artichoke-roots is not the same species as those 

 from the mangold-wurzel, for the antennae are longer and stouter : 

 and whether those Mr. Haliday has observed under marine re- 

 jectamenta are identical with the former I cannot ascertain at 

 present. 



These insects belong to the Order Coleoptera, Family 

 Stlphid.e, Genus Silpha, and the species is referred to 

 S. opaca. 



The eggs are laid probably in the earth, but this remains to be 

 proved ; and the larvae must have been hatched ten or twelve days 

 when first observed, as they were 2 lines long (fig. 13) ; when full- 

 grown they are 4 or 5 lines long (fig. 14). They are very much the 



