112 THE entomologist's RECORD. 



cyanide, and a couple of layers of perforated zinc (the lower one 

 being on the top of the sponge, and the next a little higher up to 

 avoid the wings touching the ammonia) taking the place of the plaster 

 of Paris. — -A. Hall, Newbury, Sheffield, A/ay, 1890. 



My " modus operandi " in killing Lepidoptera is in most cases the 

 cyanide bottle, prepared in the following manner : — Cyanide of 

 Potassium i part ; Plaster of Paris 2 parts ; Water 2 parts. 



First roughly powder the cyanide and mix with the plaster of Paris, 

 then add the water ; thoroughly mix and quickly pour into suitable 

 bottles ; when set, place a layer of white blotting paper on the top, 

 for the purpose of absorbing any exudation from insects caught at 

 sugar on freshly- emerged specimens. The above form will be found 

 to constantly give off vapour of cyanogen until all chemical action has 

 ceased. Usually I only charge my bottles once during the season. 



Chloroform I find mvaluable for all green coloured insects, more 

 especially the HylopJiila family, the colour of which cyanide quite 

 destroys, leaving them a rusty brown. Chloroform I also find the 

 best for all Tinece} 



Laurel leaves owe their virtue to the same source as the cyanide, 

 viz., cyanogen, and I daresay are very good. 



With reference to ammonia, practically I have always shunned it ; 

 theoretically I should have thought it would have a most deteriorating 

 effect upon all green coloration, to say nothing about less brilliant 

 colours, but with all due respect to our valuable Editor, " the proof of 

 the pudding, etc." — J. P. Mutch, 359, Hornsey Road, N. 



After the experience of more than a quarter of a century, I 

 am convinced that ammonia is the best agent generally for killing 

 lepidoptera. In my early collecting days I commenced with laurel 

 leaves, but specimens so treated became so stiff as to render 

 setting, after I had learned to be critical in this respect, most ditificult. 

 I then turned to the cyanide of potassium bottle, and found this but 

 little improvement ; so the cyanide of potassium bottle was discarded. 

 I then tried ammonia (the solid lumps of sesqui-carbonate as recom- 

 mended by Dr. Knaggs in his invaluable Lepidopterisf s Guide), and 

 have used it now for more than twenty years. In the case of large 

 species, such as the Sphinges and some of the Bomeyces, I usually put 

 these into the bottle just before retiring to bed, and in the morning they 

 are in a beautifully relaxed condition for setting. Small insects — most 

 of the Geometr/E, in fact — I found ready for setting in about six or 

 eight hours, and I do not prefer that these should remain in the bottle 

 longer. T need not say that each insect is first put into a comatose 

 state with chloroform. But it must be remembered that amnioma 

 cannot be used for all species of lepidoptera. It is well known that 

 green - insects are irretrievably ruined by it. And my experience is that 

 it is not suitable for many of the Rhopalocera. Black and dark- 

 coloured species, such as Limcnitis sibylla, Apatura iris, the Erebias, 

 Satyrs, and the Theclas are not improved by its fumes ; they are rendered 

 somewhat rusty by it. The appearance too of C/irysopha?ius phlixas is 

 quite changed by ammonia, the brilliant metallic copper gives place to a 

 dull washed-out brown, and if left in sufficiently long, the copper colour 

 ^ These can be killed just as well with ammonia. — Ed. 

 ^ Not all if carefully used. — Ed. 



