1890.] THE YOUNG NATURALIST. 



159 



assumes, that those observers who have recorded actual cases of 

 migration, are mistaken, and have recorded as seen, that which they 

 have not seen. This seems the plain English of the matter. 



That insects have been seen in an actual state of migration goes 

 without saying. If proof is wanted, I would suggest that those who 

 have never done so, should read " The Naturalist in Nicaragua,"" by 

 Thos. Belt, F.G.S., or "Migration of insects," Entomological Monthly 

 Magazine, Vol. XXIV., p. 204, by the Rev. Canon Fowler. To go 

 behind facts to find arguments which shall prove that facts are not 

 facts, seems unreasonable. 



Now with regard to "immigration" and "migration!" Migration 

 being an actual fact, may I ask what the second paragraph (97) 

 means ? 



Have we any warrant for assuming that insects have no "migratory 

 instincts"? Given the fact that insects do migrate, are we not fairly 

 safe in assuming that they have "migratory instinct"? I do not 

 believe in "involuntary migratory instinct" — whatever they may be 

 — but I believe the migrations of insects are as perfectly voluntary as 

 those of birds, but, so far as we at present know, less regular. 



Relative to the third paragraph (p. 97), Mr. Sharp states a fact 

 when he says that the specimens he saw in the summer would be 

 equally fresh in Germany and Sweden. No intelligent lepidopterist 

 would argue that the specimens seen were immigrants, but their parents 

 (the spring specimens which produced those seen) probably were. 



To turn to the fourth paragraph (Vol. X., pp. 97, 98). Why 

 assume that the coasts of France, Holland, and Belgium supplied the 

 immigrants ? Would not any part of the area in which D. galii occurs 

 do for a starting place ? And, since all observed migatory swarms have 

 been noted as covering an immense area, can we assume that on 

 settling they should all alight in one spot ? Is it not more reasonable 

 to imagine that they would gradually leave the swarm, as food and 

 suitable conditions for settlement were found, and gradually disperse 

 over a large area in the direct line of migration. And if Mr. Sharp 

 will trace out where the greater number of specimens of D. galii were 

 captured, he will find it bears out my view. As for " making for 

 certain spots, &c," this is ridiculous ! The larvae were captured here 

 and there, all over that area of the country through which the flight 

 appears to have occurred, but Avere turned up in abundance only in 

 those localities, where a few expert lepidopterists were located, and 

 * Some extracts are printed 'Entomologist,' Vol. VII., pp. 60, 61. 



