1900] GAMMA OR SILVER Y-MOTH. 55 



still few in numbers and small in size about July 12th ; that about 

 a fortnight later, on attention being drawn, by the multitude of 

 starlings upon the Mustard crop, to something unusual occurring, vast 

 numbers of caterpillars were observed, then advanced in growth and 

 causing much damage, of which estimate is given ; that at date of 

 writing, Aug. 3rd, the caterpillars had turned to chrysalis state ; and 

 also that no great numbers of this Gamma or Silver Y-Motli had been 

 previously noticed ; also attention is drawn to the very practically inter- 

 esting point that, whilst fields near to the bank of the Humber for a 

 length of ten or twelve miles were more or less affected, fields a little 

 inland were not perceptibly damaged. I append Mr. Lennard's obser- 

 vations in his own words : — 



" When I was going my round amongst the Mustard growers on 

 the 12th and 13th of July last, I noticed several small green cater- 

 pillars, but never thought of their injuring the crop. On my return 

 from my holiday I find that the attention of the farmers was drawn to 

 their Mustard about the 23rd by the great numbers of starlings upon 

 it. On examining the crop they found thousands of caterpillars about 

 an inch to an inch and a half long, which were eating the leaves and 

 the young pods, and dunny the iveek damage was done to the extent of 

 about two to four sacks per acre. 



" At the present time the pest is in its chrysalis state, of which I 

 send you specimens. I notice a peculiarity (which will probably not 

 be one to you) that in the majority of cases there are two chrysalids in 

 each cocoon, though there are more in some. I shall be obliged if you 

 will tell me the name of the moth, and also your opinion as to the 

 probability of its being present again another year. I hope it may be 

 as in the case of the Diamond-back Moth, which, though it did great 

 damage a few years ago to the Mustard, yet in the following year none 

 were to be found. 



" Amongst the peculiarities of this visitation are : — 



" No great numbers of the moth have been noticed, either in the 

 earlier part of this year or in previous years. 



"Every field near to the Humber Bank, in a length of ten or 

 twelve miles, is more or less affected, whilst those fields a little inland 

 are not perceptibly damaged. This would make it appear as if the 

 moth had come across the sea ; if it had come from the Lincolnshire 

 coast, it would have been heard of." — (H. L. L.) 



The specimens forwarded by Mr. Lennard proved to be P. gamma, 

 of which the first moths appeared from the cocoons sent on the 5th 

 and 6th of August. 



To the above communication Mr. Lennard added a request that I 

 would not at that time draw attention to the severe nature of the 

 attack for fear of causing alarm, but that later on he would send me a 



