56 MUSTARD. [1900 



full report of the infestation of the " Gamma" on the Mustard after 

 he had been round again, and had obtained all information possible. 



"In Lincolnshire," Mr. Lennard added, "it has attacked the 

 Potatoes. On the worst damaged Mustard crop here, Potatoes are 

 grown hi the next field (the headland only separating them), and they 

 are not touched ; whilst on the other side is a field of Swedes, where 

 eight rows have had the leaf completely stripped off, the rest of the 

 field being undamaged. Thistles and Hairiff have had their leaves 

 completely stripped off by the caterpillars." — (H. L. L.) 



In compliance with his promise to give me a more detailed note 

 regarding the attack, Mr. Lennard favoured me with the following 

 report, in which, in the first part (which was dated August 2nd), 

 further information is given regarding the vast numbers of the infes- 

 tation, their voracity, and their method of attack to the Mustard. In 

 the addition, dated Sept. 5th, Mr. Lennard again mentions the severe 

 damage that had been caused, and again alludes to the caterpillars 

 having been reported to have done much harm to Potatoes in Lincoln- 

 shire. Mr. Lennard wrote as follows : — 



" I am sorry to inform you that serious damage has been done to 

 the growing crops of Mustard seed in Holderness. On the 13th of 

 July I noticed several small green caterpillars on the plant, which, 

 however, looked particularly healthy ; but when I returned from my 

 holidays on the 80th, the farmers told me that their crops were covered 

 with caterpillars about an inch long, and were very badly damaged. I 

 went to see the crops again yesterday, and could scarcely believe it 

 possible that so much injury could have been done in so short a time. 

 The pest was then in a chrysalis state, millions of them hanging on 

 the plant in cocoons or webs. I send some specimens which I hope 

 may hatch out, so that you may recognize it. 



" I think the moths, in the first instance, must liave come across 

 the North Sea, as every field adjoining the Humber for a distance of 

 fully twelve miles is more or less seriously damaged — the worst being 

 to the plot, one of fifty acres, nearest the mouth of the river ; here the 

 damage cannot be less than £5 or £6 per acre, on others it will be £2 

 or £3, whilst half a mile, or even less, inland no perceptible injury is 

 done. The total damage will probably be £800 to upwards of £1000. 

 Had it not been for that best of the farmers' feathered friends — the 

 Starling — the damage would have been much more serious ; immense 

 quantities of these birds could be seen feeding on the grubs the whole 

 day long. The caterpillars are evidently most voracious feeders. They 

 first eat off all the leaves of the Mustard plants, and then the more 

 tender pods and bark ; several of the side branches are completely 

 stripped. In addition to this they eat such plants as Hairifi' and 

 Thistles, nothing being left but the bare stalk. 



