The Fly-catching habit of "Wrightia coccinea."

BY
SURGEON A. TOMES, M.D.,

BENGAL MEDICAL SERVICE.

(With Plate VI.)

      In a neighbour's garden at Midnapore are two fine shrubs of Wrightia
coccinea. They were in full bloom in April and May, and their handsome deep
red waxy-looking flowers were often observed to hold, entrapped, one or more
living and struggling flies.

      Learning from Dr. King (who kindly identified the species for me) that the
peculiarity in question does not appear to have been noted by botanists hitherto,
I have been induced to investigate the mechanism of the trap with a view of
discovering the meaning of the habit.

      The flowers of this Wrightia have a very strong attraction for insects.
This is owing to their gaudy colour, to their possessing a peculiar heavy vinous
smell, and to the secretion of a syrupy liquid which bathes their internal surfaces.
So strong is the attraction that while I was engaged in the dissection of a
specimen, a portion of the perianth lying on my table was promptly discovered,
seized, and carried off by a hungry cockroach.

      The insects found entrapped were almost invariably common house flies
caught by the proboscis, but occasionally a rather large species of ant caught
by the neck, in a trap formed by the stamens (see Fig. I, pl. VI).

      On certain days dozens of flies would be caught thus, while on others not
one would be seen.

      On one occasion a single flower had succeeded in imprisoning four flies
all at once, while two flies were often to be found in the same flower.

      The insects after capture were not digested, but died a lingering death, and
were devoured by red ants, which appeared to swarm over the tree. A fly which
I released from the trap after a long detention seemed to be none the worse
except for a bruised and swollen proboscis.

      The "trap" is formed by the andrœcium in this way:—The flowers are
pentandrous; the 5 stamens, somewhat arrow-headed in shape, are of strong
woody consistence, and each is bordered by a stiff narrow wing or membrane
(see Fig. 3, pl. VI, a and b). They spring from the perianth, and converging
surround the pistil in the form of a cone, closely embracing it at its upper part.

G