OBSERVATIONS ON ACHERONTIA ATROPOS. 151 
June. I am also aware of other instances where the results have 
been the same. The few pupe I have had at various times 
disclosed imagines in June, and the earliest specimen I know of 
from hybernated pupa was bred on the 27th of May. I think 
it probable, therefore, that specimens of atropos seen here early 
in May have not emerged from pup in this country, but that 
they are immigrants. 
This is just where the difficulty comes in with regard to 
treating pupe of atropos found in the autumn, the imagines from 
which have not emerged by the end of October. If they are of 
immigrant parentage they will probably require artificial warmth 
to bring them to maturity, but if from British stock all that is 
necessary is to keep the frost from them. Perhaps larve which 
are to produce imagines in the following year go some depth 
into the ground to pupate, where they are protected from the 
effects of ordinary frosts, while those destined to attain the 
imago state the same year pupate either on or near the surface. 
If this were so some indication of the treatment required would 
be afforded by noting the situation in the soil of the pup found, 
but, even if we could take the position of the pupex as a guide, 
we have no certain clue to their origin, and, although the 
simple precautions adverted to would suffice with pupe from 
British stock, the same thing would not do, or at least would 
be risky, with pupe from immigrant parents. I think, however, 
when larve and pup of atropos are more than usually abundant, 
we may fairly suspect that the foreign element is largely repre- 
sented, and consequently we should treat any pupe we may have 
at such times with becoming tenderness. 
In conclusion I may say that a species is none the less British 
because the representatives of such species in this country are 
the offspring of immigrant parents. In whatever country a 
species may naturally effect its metamorphoses, although it may 
not be native thereto, it has a legitimate right to be considered as 
belonging to the fauna of that country. (Of course, imagines from 
imported ova, larve, or pupz, even if captured in this country, are 
not British.) If we were only to recognise as British such species 
as were actually indigenous, I am afraid that we should have some 
trouble in drawing up a satisfactory insect fauna list. 
To what extent the insect fauna of the British Islands has 
been augmented by immigration alone since they were separated 
