OCCASIONAL ABUNDANCE OF INSECTS. 23 
ably we shall find that it is—so far as Britain 1s concerned 
—a purely imported species, and that in all probability our 
climate is not suited for its permanent residence with us.” 
Then another well known London Entomologist Mr. 
W. Tugwell, says, ‘“‘To migration I fully believe we in 
England are indebted for many other species (besides 
galit he means) but that the climate does not suit 
Deilephila galiti and it in consequence soon becomes weak 
and fails to be fully established.” 
This gentlemen also backs his opmions by the only 
piece of direct evidence, such as it is, that I can dis- 
cover to have been adduced by the migrationists namely— 
that specimens of the imagines bred by him from larvee 
he had taken at Deal, were considerably smaller insects 
than imagines taken at large on the wing; the presumption 
being that the latter were of continental origin and there- 
fore larger than the British born insects. I doubt however 
whether there was a sufficient number of the imagines 
captured in Britain at all to make the comparison of any 
value. Passing by this however, besides the citations 
just given—we have such well known authorites as Mr. 
Tutt of London, and Mr. Robson of Hartlepool, declaring 
their adherence to the migration explanation of the of 
Deilephila galw in these years. 
Thus we find nearly all the entomologists who have 
expressed any opinion on the matter at all going solid for 
immigration and it would be one feels, a somewhat 
presumptuous and even reckless thing to question an 
opinion so united and so authoritative did one not harbour 
a faint suspicion that this singular unanimity might be 
due less to the conviction of the strength of the evidence 
which supports their theory, than to the natural dislike 
we all feel to suspended conclusions, or the admission of 
complete ignorance as to the true solution of so notorious 
