THAYER'S VIEWS 205 



of a typically aposematic butterfly, Acraea egina. This 

 brilliant black and scaiMet species could be seen in great 

 numbers on the open grass land near the well defined border 

 of the dense forest which, as has been described, ends 

 abruptly, presenting a dense wall of greenery among ' 

 which one searches in vain for scarlet flowers or any patch 

 of scarlet with which the Acraea could harmonize. Near 

 the edge of the forest, but often as much as a hundred 

 yards away, in the open grass land, flourish clumps of 

 the plant Erlangea tomentosa, which bears fine heads 

 of lavender coloured flowers. These are extraordinarily 

 attractive to Acrasines, which crowd together on them, 

 making a brilliant picture. Not only the black and 

 scarlet Acraea, such as egina, zetes, perenna and the 

 rarer pJiarsalus, together with smaller species similarly 

 coloured, but black and white females of Planema macarista, 

 P. alcinoe and P. aganice, the brown males of the two 

 latter, and black, orange and white males of P. macarista, 

 with both sexes of the similarly coloured P. poggei, all 

 congregate in various proportions, and being freely exposed 

 on the lavender heads of flower, make a very brilliant 

 and conspicuous assembly which by no stretch of imagin- 

 ation could be considered to harmonize with the surround- 

 ings. 



It is true that one tree with brilliant scarlet flowers, 

 known to the Baganda as " Ekirikiti " {Erytkrina tomentosa), 

 is plentiful on the islands, but butterflies do not visit 

 it, and it usually has no leaves at the time of its flowering, 

 so that the isolated bunches of flowers high up in the air 

 can hardly be considered to form a background against 

 which scarlet butterflies would be invisible. Moreover, 

 the tree usually stands by itself in open places. 



It must, I think, be admitted that such insects as the 

 above are conspicuous in their natural surroundings, and 

 the explanation, first suggested by Bates, is that these 

 are relatively distasteful species, to whose advantage it 



