30 THE ENTOMOLOGIST. 



ON A CURE FOR ENTOMOLOGICAL SPECIMENS 

 AFFECTED BY VERDIGRIS. 



By W. G. Sheldon, F.E.S. 



In the eighties and early nineties of last century I devoted a 

 certain amount of time to the smaller British moths, including 

 the Pyrales, Pterophori, Cramhites, Phycides, and Tortrices. 



Towards the end of that period verdigris began to show very 

 pronouncedly in the specimens belonging to these groups, and 

 chiefly for this reason I ceased to collect them, and beyond 

 removing at long intervals specimens that had become hopelessly 

 affected they were scarcely looked at. 



In those days no cure was known, at least to me, and I take 

 it one of the principal reasons why the micro-lepidoptera are now 

 so little studied is this verdigris trouble. 



During the last few years I have devoted some time and 

 thought to the problem and a possible remedy, and have eventu- 

 all}^ evolved a method which has proved successful, and which I 

 am induced to make public in the hope that it may prove useful 

 to my brethren of the net. 



It is, of course, known to every lepidopterist that the pins 

 made of an alloy into which silver largely enters, and which are 

 sold by Messrs. Watkins and Doncaster, are said to be proof 

 against verdigris, and there is every reason to believe this is so, 

 for my friend, Mr. J. Hartley Durrant, informs me that they 

 have been used at the Natural History Museum for many years, 

 and that he is not aware of a single specimen for which these 

 pins have been used that has developed verdigris sufficiently to 

 affect its value as a specimen. I should say that there is something 

 in the alio}' which sometimes permits a slight coating of verdigris 

 to form on the pin, but this is never sufficient in quantity to cause 

 any damage to the specimen. 



Of course it is a very simple matter to prevent verdigris from 

 developing on a newly-killed specimen by using a silver pin, but 

 the difficulty has been to cure old specimens which have developed 

 verdigris around the pin that was used for them years ago. 

 Macros can usually be relaxed and successfully reset on a new 

 pin, but it has not been so easy to satisfactorily relax and reset 

 the smaller fry. 



The difficulty I have found, and no doubt others also, is the 

 liability these moths have to spring after having been relaxed ; 

 so much has this been the case that it has been usual to dispense 

 with the damping box altogether, and to set the specimens imme- 

 diately they were killed. 



This difficult}' no longer exists. 



My old specimens were set on black pins, which at that date 

 were advertised as proof against verdigris. We now know that 

 of all pins that were ever made they are the most prone to it. 



