Venus Flytrap growing

The mechanism by which a Venus flytrap moves is poorly understood. When the trigger hairs on the trap are stimulated, an action potential (mostly involving calcium ions) is generated, which propagates and stimulates cells. Exactly what this stimulation does is not clear. Cells in the flytrap may rapidly secrete protons into their cell walls, thereby loosening them and allowing them to swell rapidly by osmosis. Alternatively, cells in the flytrap may rapidly secrete other ions, allowing water to follow by osmosis, and the cells to collapse. Once the trap has rapidly shut, the bug will continue to stimulate the inner surface of the trap, causing a further growth response forcing the the edges of the trap to close and eventually sealing the trap ready for digestion.

Contrary to popular belief, Venus flytraps do not make acids. The digestion process is in fact caused by enzymes secreted by glands in the trap. The enzymes reduce the protein in the bug, reducing it to a skeleton. The trap then reopens, ready for reuse. Traps typically only open or close three times before dying.

More detailed information about the movement process can be found on the Venus flytrap Wikipedia page.

Photo courtesy of Jamie Duke.

Unsurprisingly, Venus flytraps are not able to digest the hard exoskeletons of most bugs. Only the proteins and other digestable ’squishy’ bits of the bugs your traps catch (or are fed) are digested. Digestion of the ’squishy’ bits is catalysed by enzymes secreted by glands in the lobes of each trap. Most traps finish the digestion process within 10 days. After this they open back up, leaving the skeletal remains of the bug.

The number of bugs your traps can digest before dying depends on how healthy your flytrap is. As a general rule of thumb, most household Venus flytraps catch two to three bugs before turning black and dying, but if you keep your plant in tip-top condition, then they may be able catch many more.

Note the sunken eyes of the digested fly in the photo above. Photo courtesy of Peter Millis.