Rhodora 
JOURNAL OF 
THE NEW ENGLAND BOTANICAL CLUB 
Vol. 5 October, 1903 No. 58 
INSECTICIDES USED AT THE GRAY HERBARIUM. 
B. L: ROBINSON. 
One of the questions most frequently asked by visitors at the Gray 
Herbarium is what means are employed to prevent the insect depre- 
dations to which all large collections of plants are to a greater or less 
extent exposed. ‘This interest in the matter leads to the belief that 
it may be worth while to record the methods, which have been 
adopted, after a varied experience of many years, in dealing with 
this problem. 
Until about 1885 it was the custom to poison with corrosive subli- 
mate all specimens placed in the organized part of the Gray Herba- 
rium. This was done in two ways. The first and crudest was to 
paint the specimens, after mounting, with an alcoholic solution of the 
sublimate, much to the disfigurement of the sheets. This way was 
soon abandoned as a general method and only resorted to in cases 
in which it was found that a sheet, already mounted, was infested by 
insects. The second method, used for many years, was to dip each 
dried plant, before mounting, into a shallow tray of the same solution 
and then dry it between blotters. This mode of procedure is, with 
various modifications, the one now followed in many private herbaria 
and in several of the great European collections. There is no doubt 
that it has a certain efficiency, but it also has considerable disadvan- 
tages. The slowness and expense of the treatment, while not bur- 
densome in collections of moderate extent, become much more seri- 
ous when the number of specimens mounts to many thousands 
annually. However, these are not the chief drawbacks. There is 
the difficulty of keeping an alcoholic solution at such a point of 
