Observations on Insects affecting the Turnip Crops. 71 



and Essex. Monsieur Desjardins says'^ that it exists also in the 

 Mauritius^ where it makes very great ravages in the kitchen- 

 gardens ; but whether it is indigenous to that island^ or has been 

 transjiorted from Europe with the cabbage-plants that the people 

 cultivate there, is unknown. I have little doubt that this was the 

 caterpillar which Mr. Dalgavings of Forfarshire mentioned as 

 having seriously injured his crop of turnips in 1826. I am, 

 however^ particularly desirous of calling the attention of agricul- 

 turists to this enemy of the turnip-crop in consequence of having 

 received the following communication from Mr. J. Weaver, who 

 lives in the neighbourhood of Petersfield, Hants: — ^^The litde 

 moth which I have sent is one from a host of small green cater- 

 pillars which have been exciting some surprise here this summer. 

 About the beginning of August I was directed to a field of turnips 

 said to be infested by the ' niggers :' they proved however to be 

 myriads of tiny larva?, averaging perhaps half an inch in length 

 each, slender, and somewhat tapering at both ends, and of a green 

 colour when full fed. They were exceedingly active, and on the 

 slightest touch would wriggle themselves off from the leaf on 

 which they were feeding, let themselves down by a silken thread, 

 and remain suspended till the cause of alarm had subsided, when 

 they would regain their former position. So incredible were their 

 numbers, that on a single plant of moderate size, and taken at 

 random, I counted upwards of two hundred and forty ! — and before 

 the end of the first week in August every leaf, for the space of 

 more than an acre, was completely reduced to a parched- up 

 skeleton : not a turnip escaped them, and by the middle of the 

 month you might have looked in vain for the smallest vestige of a 

 green leaf on the field of their depredations; and to this day 

 (Oct. 29th, 1837) it is as bare as if nothing had been sown there. 

 Similar patches from a like cause may be seen in two or three 

 other fields in this neighbourhood, where a most excellent crop is 

 yielded in every other part. On the 9th they began spinning 

 their cocoons, which are of the most beautiful net-like texture, 

 some on the dried fibres of the turnip-leaves and others upon the 

 ground. The perfect insects emerged about the 20th ; but out 

 of seventeen cocoons five moths only hatched, while the remain- 

 ing twelve produced the accompanying parasite." This was one 

 of the IcHNEUMONiD^, and is called by Gravenhorst 



26. Campoplex paniscus : j it is black ; the antennae are slender 

 and shorter than the body; lower part of face silvery; mouth 

 straw-colour ; body attached by a narrow neck ; the apex of the 

 female armed with a slender shortish tripartite ovipositor, like a 



* Annales de la Soc. Ent. de France, v. 6. p. 229. 

 t Curtis's Guide Gen., 529, 29. 



