It is interesting to consider the actual manner in which the plant carries out its fly-catching.
As is well known, bright colors have a great attraction for insects. In this case it is apparently the red areas on the lobes of the leaves which possess such an attraction for insects of all kinds. Possibly they secrete a sweet substance, but this is not definitely known. All goes on well as long as the creatures avoid doing one thing; unhappily, this they are almost certain to do sooner or later. Nothing happens unless the insect brushes up against one of the hairs previously mentioned as being on the surface of the lobes. The succeeding happenings are disastrous for the fly.
With really astonishing rapidity the sides of the leaf snap together so that the spines on the borders of the lobes meet. Thus, in a very brief time a most perfect little cage is devised from which any sort of escape is absolutely impossible. During the next half hour the sides draw in still closer, so that the spines overlap. At this stage the leaf pours out a copious discharge of digestive fluid, which enables the plant to make use of the nutritious element in the fly.
CRUEL PLANTS THAT ENTRAP AND KILL ANIMALS
| The light streaming through the transparent spaces induces the prisoner to waste its strength in a vain effort to escape through them. | Once below the inside edge, escape is almost impossible. Pitchers have been found almost full of flies and other insects. |
| Absorbed in the delights of feasting on the nectar of the Nepenthes, the insect wanders with fatal ease down the fluted rim. | The fruits of the Martynia fasten themselves to passing animals that sometimes get the hooks caught in their mouths and die a dreadful death. |
After an interval of several days the leaf of the Dionæa opens and allows the hard carcass of the fly to roll away. The plant is then ready for another meal, and unable to realize the fate which is in store for it, another fly falls a victim. Quite often the Venus Fly Trap is able to capture large insects.
THE STRANGE HABITS OF
THE NEPENTHES
Scattered over the tropics of the old world there is a remarkable group of plants known as Nepenthes. Many of these are of a climbing habit, rooting in bark crevices where a little moist soil may have collected. To augment their food supply they have produced pitchers, which in some species are of great size. Indeed, in one kind of receptacles will hold as much as two quarts of water. In all cases these pitchers have a thick, corrugated rim, and it is this which plays a big part both in the luring and the capturing of the insects. On this rim, as well as on the lid of the pitcher, there are honey secreting glands, and these, of course, make the strongest appeal to hungry insects.