1889.] FLOUR MOTH 181 



working, and, still more, if you know how to destroy it, I 

 should feel greatly favoured and obliged by any information 

 that you may kindly give. I believe that unless it has 

 very recently been placed on your American lists of Lepi- 

 doptera it is not noted as known there, and I am trying to 

 persuade myself that it is not all selfishness which makes 

 me trouble you thus, but that if by any possibility you may 

 not chance to have heard of the serious nature of the work 

 of these larvae, you may care to have a few lines about 

 them. The moth is about f in. in spread of the fore-wings, 

 which are of pale grey with darker transverse markings ; 

 the hinder wings remarkable for their whitish semi-trans- 

 parency with a darker line from the point along a part of 

 the fore edge. The larvae, when full-grown, as far as I see, 

 are about five-eighths of an inch long. You will not care 

 to have full description, but they have surprising instinct 

 for travelling, and amazing strength. One that I watched 

 to test this power escaped from under a little smooth-edged 

 cardboard frame which I had placed on a woollen cloth on 

 a quite flat table and pressed down with a one pound 

 weight. 



I hope before long to forward my twelfth Report for your 

 acceptance and that it may meet your approval. 



June 22, 1889. 



I have not until to-day been able to find time to study 

 your interesting and instructive Report (which reached me 

 a little while ago), and now after my best thanks I hasten to 

 offer some observations about our use over here of the word 

 paraffin see p. 104 of your Report. So far as I know or 

 can learn, the different oils sold under the name of paraffin, 

 kerosene, or crystal oil, only differ from each other by 

 reason of treatment to secure various degrees of purity or 

 refinement. The common paraffin oil is the coarsest ; 

 kerosene I understand is a little more refined, and a trifle 

 higher in price ; and crystal oil or (as it is sometimes 

 described in the trade) "Ai Crystal Oil" is limpid like 

 water, and the purest of all. I do not know why, but 

 kerosene is a name little used here. Paraffin is certainly not 

 a correct term for the fluid form, but this fluid or oil is used 

 so enormously compared to the solid paraffin that the 

 appended word oil necessary for correct description is 

 usually omitted as being understood. I quite feel it is a 

 loose and inaccurate plan, but so the matter stands. In 

 the same number of my Annual Report from which you 

 quote namely, that for 1884 published 188531 pp. 66-67, 



