1900] GAMMA OR SILVER Y-BIOTH. 57 



" Sept. 5th. I regret to say I have in no way underestimated the 

 damage done to the Mustard by the caterpillar of the Gamma Moth 

 (as recognized by you) ; now that the crop is cut I can speak with 

 certainty. 



" I understand that in Lincolnshire Potatoes have suffered serious 

 injury from the same insect." — (H. L. L.) 



The following observations refer to the appearance of the Gamma 

 caterpillar, and were sent me by Messrs. W. J. Coleman & Sons, of 

 South Side, Covent Garden, London, W.C, on July 31st : — • 



" We are growers of Maincrop Potatoes in the district of Holbeach, 

 Lincolnshire, and within the past ten days the haulm of this description 

 of Potato has been seriously attacked by a green caterpillar about one 

 and a half inches long, which may involve the loys of half the crop. 

 The Potatoes had previously been sprayed with Strawsonite, and 

 sprayed with a mixture of soft-soap and paraffin since the appearance 

 of the caterpillar, but without effect. We enclose you specimen of the 

 bine, or haulm, with some of the chrysalids, as we do not remember 

 such an occurrence previously. We may add that other sorts of 

 Potatoes do not at present appear to be affected." — (W. J. C. & Sons.) 



On August 2nd Messrs. Coleman further wrote tluit, as the point of 

 identification was of material interest owing to the many thousands of 

 acres of the above-named kind of Potatoes grown both here and in Scot- 

 land, they had asked their agent at Holbeach (Lincolnshire) to send me 

 some fresher specimens of the Potato-haulm, the caterpillar, and the 

 chrysalis, and samples were accordingly forwarded to me from Hol- 

 beach, Lincolnshire, on August 3rd by Mr. Canwell. 



These, as well as the specimen sent me by Mr. Lennard, proved to 

 be of P. (/amma, from which, on the followhig day (the 4th), I found 

 the moth had begun to develop. In this case I was fortunate enough 

 to have the infestation in all three stages — that of the green " semi- 

 looping " caterpillar with the two pair only of abdominal sucker-feet ; 

 of the chrysalis with the almost spike-like process beneath it ; and 

 of the moth, characterized by the white Y-like figure on the upper 

 wings, from which it takes- its common English name. 



The above notes are of a good deal of interest, as showing the 

 capacity of this Silver Y-Moth of causing very serious injury over a 

 large area to two important crops, neither of which appears to have 

 been previously recorded as infested, excepting in the two instances 

 noticed at p. 53, when the caterpillars, having in one locality 

 "cleared" the Clover fields, and in the other eaten all of the "young 

 shoots of the Clover," migrated in search of food to the neighbouring 

 Potatoes. 



1)1 regard to the came of the jmst year's attack, I should conjecture 

 from the evidence given, that it might reasonably be supposed to be 



