NEWLY-OBSERVED HABIT IN THE BLACKCAP WARBLER. 171 



The salient features in the observation are, I think, remark- 

 able : — (1.) The fact of the bird choosing the only spot where 

 the liquid occurs, in order to make the opening in the calyx 

 which is to serve as the bait for the insect. (2.) The visit of the 

 insects paid directly to the calyx, and not to the flower. (3.) The 

 fact that the humble bee, which so commonly makes this kind of 

 aperture in the fuchsia and other flowers, should in this instance 

 make no approach to the calyx. (4.) That the punctures are, so 

 far as I have observed, made only by the male bird, never by the 

 rufous-headed female. 



The honey bee, which visits in large numbers a tree close by, 

 never approaches the Hibiscus, 



March 18. — I found, on further investigation, that the flowers 

 of the pink variety of Hibiscus Africanus do not secrete any 

 nectar, and are but little visited by the humble bee. The cause 

 appears to be that the corolla overlaps at the base much more 

 closely than in the scarlet flowers, so that no opening is left for 

 the proboscis ; in the scarlet there is an opening. Can it be that 

 the nectar under the calyx is due to the irritation caused by the 

 vent of the humble bee ? I think it clearly is so. The scarlet 

 flowers which occur on the trees with the pink variety always have 

 nectar, and the calyx torn — the pink flowers never. 



Monte, Las Palmas, Grand Canary, March 22. — I find that 

 Hibiscus Africanus has been treated here in the same way by the 

 " Capirote " (Sylvia atricapilla). But I also find that Abutilon 

 frondosus, another plant of the Hibiscus family, has undergone a 

 similar mutilation of the calyx. In this instance, however, there 

 are notable differences. The base of the calyx has nectar all 

 round the receptacle, and not, as in Hibiscus t on two spots mid- 

 way on the inner surface of the two upper segments, — hence the 

 openings are made in each segment, — and they are made not by 

 the Blackcap Warbler, but by a black-headed Tit with bluish- 

 green body. The object seems to be — but I cannot be quite 

 sure of this — to enable it to get at the ants, which come to the 

 nectar in large numbers. In the case of the Hibiscus they do not 

 enter the calyx, and only a few visit the flowers apparently to milk 

 the Aphides, and these are not found on the Abutilon. There are 

 not many winged insects visiting these flowers, except a large 

 species of wasp. 



The Titmice visit the flowers in succession, tearing out large 



