THE VARIOUS MODES OF EMERGKNCE. 



109 



The existence of specific and geographical variations m the number 

 of the individuals of various species is so well-known that it suffices 

 to mention it. briefly. For the most part it is a case of true and proper 

 geographical variations, which has nothing- to do with particular 

 specific tendencies, and there al\va,vs exist localities where even the 

 species which are generally more abundant can be sporadic, more or 

 less (at the Baths of Valdieri, in the Maritmie Alps, Pararge viegera, 

 L., has been found once only during various years of assiduous 

 collecting by Tarati and myself), and where the species most diffused 

 everywhere are wanting [Coeiionynijiha jiamp/riliis at Valdieri itself), or, 

 on the contrary, there are localities where a generally rare species is 

 abundant (in the valley of the Fegana (Lucca) the g $■ of Lnireia 

 dorilis, Hufn., were found in abundance in 1915, together with a few 

 $ ? ), but there seems to be also a constant tendency in single 

 species to multiply in great numbers or to remain scarce in whatever 

 locality and in whatever environment, which cannot be explamed except 

 as a true and proper specific characteristic ; we cannot explain bow, 

 in some instances, they can continue to reproduce and to maintain 

 themselves so diffused in every kind of locality with a very small 

 annual number of individuals ; Loweia dorilis is an example of this, 

 and it is to be noted t,hat also in the Fegana Valley the 5 $ were 

 very few; another case is that of -4 /-mfl wedon: though much more 

 abundant than L. dorilis and also more diffused than the latter, there 

 never develop in any region of Europe a number of individuals to be 

 compared to those of other Plebeiidi {argns, icarus, thetis, etc.). Among 

 the specific characteristics one can therefore note " scarcity " or 

 " relative abundance " of individuals. 



Another characteristic is presented by the " localisation " or the 

 "diffusion" of the various species, and in this case also one must 

 perhaps distinguish between " geographical " localisation determined 

 by environment, amongst which in the first place comes the distribution 

 of vegetation, and then purelj' " specific " localisation, which some 

 species present constantly everywhere, even without apparent reason. 

 Amongst these last we may note the distinct tendency of the <? J of 

 AntlwcJiaris carda)iiines to fly, often m great numbesrs, in determinate 

 restricted zones (small portions of brooks, paths, etc.), from which 

 they do not wander ; in general the $ J of Lepidoptera are much more 

 localised than the 3' S , and they wander less from the place where 

 they emerged and where they deposit their eggs; therefore the 3' may 

 be scattered abundantly in a region and the observer may never see a 

 5 , if he doesn't discover the " centre " of production of the species ; 

 but in the case of cardamines precisely the opposite happens, because 

 the 2 is much more scattered and wandering, and is not more 

 frequent in the zones where the <? is found ; this and other similar 

 examples denote a real tendency in certain species to unite in restricted 

 areas and remain there ; perhaps the sociability shown by many 

 species is not extraneous to this, as one always finds two or three 

 individuals flying together when there are no others in the 

 neighbourhood. 



Finally, there are in the various modes of emergence of Lepidoptera 

 differences inherent in the sex ; as a general rule, there emerge first a 

 certain number of J <? , and the J 5 begin to emerge some days after, 

 and continue to emerge later than the other sex ; the Satyridae 



