172 THE entomologist's RECORD. 



the brood will, on emergence, be alike to an unusual degree, and this 

 brings me to a point which baffled me for a long time. I have bred 

 under different conditions both Continental pupae and British (insular) 

 pupae of V. to and V. itrticae. It was first with British pup^ of the 

 latter species that I found it impossible to produce the same results by 

 the influence of high temperature, as with continental pupae {vide 

 antea, pt. 4, 1909). There was comparatively less change in the 

 former. The pup^e from insular larvae resisted the influence of high 

 temperature much more than did the ■ pupse from continental larv«. 

 On the other hand, the insular pupae gave way more easily to the 

 influence of cold and darkness than the Continental ones. One of the 

 reasons for this appears to lie in the cnntrastless insular climate {ride 

 Entoiiioloifist, vol. xlii., p. 311) due in great part to the liiniiidity of the 

 atmosphere. This influence would in nature mainly take effect in the 

 larval stage. That the British climate exercises a special influence is 

 well known. In many moths it induces melanism, more or less 

 indirectly, and favours certain atavic forms {ride Tutt, Melanifun and 

 Melanochrvism. in British Lepidoptera, pp. 42, 43). The effect on V. io 

 and V. urticae appears most plainly in their uppersides* — the 

 influence on these species is not too strong, and their undersides 

 (comparable, so to speak, with the upperside forewings in most 

 moths) are too well adapted to their habits to be »iiich altered — and 

 from the results of my breeding-experiments with pupte which plainly 

 were affected by constitutional tendencies in the larvae, I suggest that 

 especially specimens of V. io ab. darariolacea (compare the insular 

 forms of T'. io var. (jeisha, Japan, var. sardoa, Sardinia, also specimens 

 from continental Asia), but also ab. nif/rifasciata, are characteristic 

 of the British insular climate, and in V. urticae the same seems 

 to be the case with ab. fiarotessellata, Rynr., ab. s^alnionicolor, Rynr., 

 and ab. infascata, Rynr. The ab. infnscata is sometimes very dark 

 red-brown in the ground-colour (when stimulating conditions of 

 development act with the constitutional tendency induced by humidity), 

 more often it is pale brown-yellow, covering the tendency to var. polan's. 

 Larvae are thirsty creatures generally, and, in a climate in which the 

 sun's heat is not very great, humidity of the atmosphere (suggesting 

 condensation as opposed to evaporation induced by dryness) would 

 draw less on the resources of their bodies than would dry air. This 

 effect is clearly noticeable in the perfect insects in Britain (compare 

 Drinkimi Habits in Butterfiies and Moths, p. 2, by Mr. Tutt) which 

 rarely congregate in numbers round puddles, etc., on roads (I myself 

 only witnessed one case) as they do in lands where the sun is hotter, 

 clearly proving that these insects are less thirstj" in a contrastless 

 temperate climate. Near Desenzano, on the Lago di Garda, I once in 

 August found the road alive with " blues," and with a cyanide-bottle 

 two inches w'ide at the mouth, I covered 53 specimens of the short- 

 tailed blue (among them were two females) which had assembled thus 

 closely to drink. 



* The uppersides of butterflies, which rest with closed wings, do not come 

 under the influence of " selection of the best-protected " as do the uppersides of 

 moths, which rest with wings spread out, and therefore the uppersides of butterflies 

 with their bright colours are specially well-fitted for the study of the direct action 

 of meteorological factors. 



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