88 THE ZOOLOGIST. 



End. Strange to say, there were still a few nesting in Gray's Inn Square. — 

 John Young (64, Hereford Road, Bayswater). 



The Stock-Dove in Ireland.— I shot a Stock-Dove here on Jan. 6th. 

 It is a level wooded locality about twenty miles from Ravensdale, where Lord 

 Clermont recorded the first Stock-Dove in Ireland (Zool. 1876, p. 4798). 

 I have shot many hundreds of Ring-Doves here, but have never secured 

 a Stock-Dove before. — G. H. Pentland (Black Hall, Drogheda). 



INSECTA. 



A Proposed Explanation as to the Appearance of Light- and Dark- 

 coloured Butterflies during the Day. — Dr. Gregory, in his ' Great Rift 

 Valley' (pp. 275-6), has made some original suggestions on the colours of 

 butterflies as observed by him in East-Central Africa. He writes as 

 follows : — " Another point which interested me in reference to insect colora- 

 tion was the influence of the different capacities for the absorption of heat 

 possessed by different colours. A black object becomes more heated than a 

 white one, when both are exposed under the same conditions. An insect 

 has so much surface in proportion to its bulk that dark-coloured species are 

 heavily handicapped when exposed to the intense sun of the tropics. This 

 is the simple explanation of the fact, which impressed itself upon me as soon 

 as I began to collect butterflies, that the light-coloured species fly in the 

 daytime, and the dark ones in early morning and at dusk. I made con- 

 siderable collections at Ngatana, at all hours of the day, to test this point. 

 Thus on Jan. 30th I began collecting at 5.45 a.m., and found only species 

 which are mainly of dark brown colour, such as Hypolimnas misippus and 

 Junonia delta. At 6.30 a reddish-brown species, Limnas klugl, began to 

 appear, and this was the only species caught during the next half-hour, 

 though this was abundant. A little before half-past seven a light brown 

 species, Acraa ccecilia, made their appearance, followed immediately by 

 numbers of light-coloured butterflies, such as Teracolus syrtinus, which is 

 all white except for a red tip to the wings, and Catopsilia pyrene, which is 

 wholly of a light creamy white. The dark brown forms disappeared from 

 the open steppes before seven, and they were followed into obscurity by the 

 light brown Limnas, of which not a single specimen could be found during 

 the heat of the day. Then the open 'barra' was tenanted only by white 

 and light coloured species. This rule, however, is not universal, for other 

 factors modify it. Thus in dull cloudy weather the dark-coloured forms fly 

 abroad all day, while some species of rapid flight habitually do so, such as 

 many of the swallow-tail butterflies. Papilio demolcus, for example, a 

 common species in the Sabaki and Tana valleys, was met with at all times 

 of day ; but it lived mainly under trees, darting out across open places from 

 one shady place to another." 



