TO TRACTS ON VARIOUS SUBJECTS, &c. 



No 1, contained 18 lively clnysalids, and 12 healthy grubs : 

 these are six more than were put in the box. This increase I con- 

 ceive to have been occasioned, either from some extremely small 

 grubs in the soil having escaped notice, or from eggs having 

 been hatched after the experiments were begun. 



No. 2, contained 16 chrysalids and 6 strong fat grubs : two 

 must have died. 



No. 3, contained a single chrysalis. — This possibly proceeded 

 from one of the grubs, at the time it was put in, being in readi- 

 ness for transformation ; and consequently it escaped the fate of 

 every other that was put in that box. 



No. 4. In this box not a grub or chrysalis was to be found, all 

 had perished ; not even their remains were to be discerned. I 

 think it therefore probable that the wood-lice (oniscus armadilla), 

 which were found in great numbers, particularly in No. 3 and 4, 

 had devoured the bodies of the dead grubs. 



After the examination on the 23d of October, the grubs and 

 chrysalids belonging to No. 1 and 2 were replaced in their 

 respective boxes, and four young mangel wurzel plants were set 

 in each, and watered. On the morning of the following day the 

 plants in No. 1 and 2 were all destroyed : whilst those in No. 3 

 and 4 are still in a thriving condition. 



On the 30th of October, one of the chrysalids taken from box 

 No. 1, and put into a glass, covered with thin gauze, produced a 

 grey moth. 



I have been induced to give this minute detail of the experi- 

 ments, as I think it may convey some useful information upon a 

 subject that is interesting to agriculturists ; for I remark, in a late 

 publication, wherein several modes for the extirpation of the grub 

 are pointed out, that the author concludes with this observation. 

 " But notwithstanding these judicious remarks, much still 



