A Note upon the Way in which Bees settle on Flowers of Derris thyrsiflora, and the Injury resulting from their Search for Honey.
By I. H. Burkill.
In the Botanic Gardens, Singapore, there is a large plant of Derris thyrsiflora, Benth., climbing over a tree of Cyrtophyllum fragrans, DC., near to the Director's house. Its stem has a circumference at the base of eighty centimetres; and it ascends to nearly 20 metres. When in flower it is very conspicuous, and attracts enormous numbers of bees, whose hum on the flowers is heard all day. Among the bees are Apis dorsata, L., Apis indica, F. Xylocopa lalipes, F. rarely X. aestuans, L., Anthophora zonata, L., and Melipona sp. Occassionally a butterfly visits also.
Owing to the height at which the flowers stand, it has been extremely difficult to take the insects; and the list is consequently imperfect.
The flower of Derris thyrsiflora in face and in side view × 2: the standard and right ala showing the places most injured by the bees.
The flowers are white with an undefined line of green down the centre of the standard. Their form is seen in the figures above.
In all their parts oxidation develops a black pigment: and by means of this it has been interesting to observe the injury which visitors do to the flowers; for injury results in oxidation.
The mechanism of the flower is typically papilionaceous. There is abundant honey within the staminal tube: the approach to it is by a wide opening upon either side of the free upper filament allowing easy access to those insects which can force apart the standard and the interlocked wings and keel sufficiently. The one
