i6o THE YOUNG NATURALIST. [August 



knew in time that they should be looked for. The great centres of 

 our working lepidopterists are London and Liverpool, both have large 

 areas suitable for D. galii at no great distance, and hence the excess 

 of the captures at those places. Directly Messrs. Harwood, J. A. 

 Cooper, and others knew that the species was about, they found 

 plenty on the Essex coast, but Mr. Cooper was late, or he says he 

 should certainly have got more. Had other entomologists known in 

 time, more would have undoubtedly been got. 



With regard to the next paragraph (Vol. X, p. 98) " involuntary 

 migration " on a large scale, seems to me ridiculous, and I must own 

 I see but little common sense in the phrase ; besides the influence of 

 the wind has very little, in my opinion to do with the direction of an 

 insect's flight. Insects nearly always fly up against the wind, and 

 some of my most successful collecting has been done in a gale. This 

 paragraph again seems, too, to show that Mr. Sharp does not clinch 

 the theory of migration. Lepidopterists, as a body, do not believe 

 that the excessively large numbers sometimes found in a given season 

 are immigrants. Last year (1888) we believe the batch of D. galii 

 imagines, which were captured, were immigrants, but not their larvae. 

 So in 1877, we look upon the May and early June specimens of Colias 

 edusa as undoubted immigrants, but we know the July and August, 

 and the October and November broods* were the progeny of these 

 broods, and not immigrants, so the parents of the summer (1879) V. 

 cavdui were probably immigrants, not the summer specimens them- 

 selves. 



Will Mr Sharp kindly answer me a practical question ? If Mr. 

 Tugwell is not right, and if D. galii is an indigenous species acted on 

 by " occult influences," why did those pupae which were collected last 

 year, and placed under artificial conditions (to resemble a warmer 

 climate), produce imagines with scarcely an exception, while those 

 which were left exposed (in an apparently natural condition), almost 

 entirely failed to do so ? Was this due to these " influences " ? 



I am sorry to take up space in the Youug Naturalist on this matter. 

 It might be better occupied. But I do not think that new members 

 to our ranks should be allowed to get false impressions, and the im- 

 pression that Mr. Sharp's papers leave is that there is no migration 

 of insects, although records of such have long existed, and the obser- 

 vations extend over many years. 



(It is due to Mr. Tutt to state that this was written some eight or 



nine months ago. In my discretion 1 held it over until Messrs. 



Briggs and Tugwell had finished their discussion on the subject. Ed.) 



*Mr. Jenner, arguing against "immigration," (Entomologist's Monthly Mag- 

 azine"), falls into the same error. No one, of common sense, has ever argued 

 that the C. edusa, which emerged under our eyes, were immigrants : their parents 

 probably were. 



