1896.] lyi 



land, to all intents and purposes fitted for its establishment here, but 

 it — possibly the agriculturists would say fortunately — will not 

 establish itself." 



The history of the gypsy moth in the United States does not 

 seem to lend^ force to the view taken by Mr. Tutt, as much as we wish 

 it might prove true, for it seems to thrive as well here as in any part 

 of the old world. America is indebted to Europe for a long list of 

 insect pests, many of which are far more injurious, because of their 

 unrestricted increase, than in their native country ; notable among 

 these are the currant saw-fly {Nematus ribesii), the larch saw-fly 

 {Nematus Erichsonii), the cabbage butterfly {Pieris rap(s),i\\e Buffalo 

 carpet-beetle (Anthrenus scrophularice) , and many others, none of 

 which show any indications of a decline in a foreign country. The 

 idea of Mr. Weir, that they were destroyed in England by collectors, 

 hardly seems worthy of consideration. I will not attempt to express 

 an opinion as to the cause of their extinction in that country, but it 

 seems to me that it must be due to causes not yet understood ; and if 

 the profound thinkers in entomological matters, of whom England 

 has so many, have not satisfactorily settled this question, it would be 

 folly for me to express any decided opinion on the subject. I wish, 

 however, to call attention to one or two points. Grreat Britain, 

 because of its insular position, the prevailing winds and currents in 

 the surrounding ocean, has a far different climate from that of 

 Massachusetts or the interior of Europe and other parts of the old 

 world, where this insect is usually most abundant. I noticed, when in 

 England, that the foliage of all vegetation seemed darker than in this 

 country, or, at least, than in the eastern part of it ; and it occurred 

 to me that this might be due, in part, to the larger amount of moisture 

 in the atmosphere, especially as quite similar conditions of climate, 

 with darker foliage occur in British Columbia, as I have been informed 

 by my colleague, Mr. E. H. Forbush, who also states that the arboreal 

 animals of that region are much darker than those in the eastern 

 parts of the United States. Some years ago, while in England, my 

 kind friend, Mr. C. G. Barrett, gave me a very complete series of 

 British Torti'icids, and I never look at my collection without noticing 

 how much darker these insects are than the same species from 

 Germany and other parts of Europe. It seems to me that this dark- 

 ening may have resulted from natural causes, operating through a 

 very long period of years. When these insects first made their way 

 into the British forests and fens, with their darker surroundings, the 

 lighter coloured individuals, contrasting the most with the objects ou 



V 2 



