Biilhophylhim macranthum , and allied Orchids. 329 
have not identified, are in flower. I have never seen it at 
other flowers of any kind, nor have I ever found it else- 
where, except on one or two occasions when I have taken 
it on the white ceiling of my verandah in the heat of the day. 
But in whatever part of the house or garden any of these 
plants are in blossom, there will always be seen one or more 
of these flies, unless the weather be too dark or wet for them. 
The three orchids I have mentioned have but little in com- 
mon, but they have all a certain amount of deep red colour 
in the flowers, the little Bulbophyllum last mentioned being 
entirely dark speckled red, and the Dendrobium having two 
deep red eyes at the base of the lip. They also all possess a 
very strong scent ; B . macranthum that of cloves, the others 
of Turkey rhubarb. I endeavoured to find out which was 
the most important of these characters, by scenting pieces of 
dark maroon leaves and other objects with oil of cloves, but 
the flies took no notice of them, although the two scents are, 
to my senses, very similar. 
The insect usually commences by licking with its short 
tongue the upper part of the sepals, both back and front. It 
eventually settles down to the front of the lateral sepals, 
especially on their dark coloured grooved apices. As long as it 
is at work in the narrow upper part of the sepals, it can hold 
on to their edges, but when it gets to the broad part, it cannot 
reach across. Its feet slip from the glassy surface, and it clutches 
wildly at the lip. Immediately its weight falls upon the lip the 
latter suddenly drops back, pitching the insect stern first into 
the column between the stelidia, which have enough springiness 
in them to separate a little and then close tightly on the 
abdomen of the captive (Figs. 5 , 6). The insect strikes the 
disc of the pollinia with the upper part of its abdomen and 
the pollinia become fixed with exact precision upon the first seg- 
ment, the lower part of the abdomen generally adhering to the 
stigma ; the lip, released by the astonished fly, instantly returns 
to its original position, and the insect is left struggling on its 
back in the arms of the column ; soon, however, it extricates 
itself, and flies away with the pollen on its back. As the 
