THE CANADIAN ENTOMOLOGIST 117 



A METHOD FOR THE PRESERVATION OF INSECT 



LARV^ AND PUP/E. 



BY F. SLATER JACKSON, M.D., MCGILL UNIVERSITY, MONTREAL. 



During the summer of 1916 the writer devised a method (as yet unpublished) 

 for the preservation of fresh-water Bryozoa in an expanded condition. At that 

 time, as a matter of experiment, several larvee and pupa? of Nymphula maculalis 

 were placed in the fluid employed for this purpose, with fairly satisfactory 

 results. It was subsequently used for the preservation of insects in all stages. 

 Among these were the larvae of Mamestra picta and other Lepidoptera, and the 

 pupa? and imagines of Physonota unipuncta, all of which seem to have retained 

 satisfactorily their form and colour. 



Several members of the Montreal branch of the Entomological Society, 

 among others, Mr. A. F. Winn and Mr. Geo. A. Moore, obtained good results 

 with the same fluid. la a letter of February 28th, 1918, Mr. Arthur Gibson, 

 Chief Assistant Entomologist, writes: "I used it rather freely for preserving 

 larvae of different kinds. ... I have also spoken of its value to several of 

 our field officers. I hope very much that you will publish your formula soon, 

 as I know many workers will find it of value." These encouraging reports led 

 to further experiment, with the view of obtaining a modification of this fluid 

 which might prove more widely useful as a preservative for material of this 

 character. 



It had been found that in many instances, e. g., in the case of large Lepi- 

 dopterous larvae, there was frequently marked alteration or loss of colour, and 

 a considerable degree of shrinkage. Pressure of other work, however, and a 

 period of incapacity for concentration of effort, led to the postponement of this 

 matter, until during the past summer opportunity was afforded for further 

 experimentation, which resulted in the provisional adoption of the following 

 method. 



The specimens, having been killed in the cyanide bottle, or by means of 

 chloroform vapour, are allowed to relax, straightened if necessary, and placed 

 in a fluid having the following composition: — 

 Fluid a. 



Cane sugar 10 parts 



Glacial Acetic acid 5 



Formalin 2 



Distilled water to 100 



The sugar is to be dissolved in the water, and the acetic acid and formalin 

 subsequently added. 



In this fluid the specimens are allowed to remain for about 24 hours. They 

 are then transferred directly to Fhiid b., which is identical in composition 

 except that the acetic acid is omitted — it being, in fact, simply a 10% solution 

 of sugar in 2% formalin. After about 24 hours this fluid should be changed, 

 and in the case of large specimens a further renewal after the lapse of a week 

 or ten days is advisable, since traces of acetic acid tend, in some instances, to 

 destroy colour. 



Attention to the following details may be of assistance in obtaining the best 

 results. 





