Our incredible jumping beans

MY MEMORY of jumping beans, when a small boy, was of a novelty toy. They were brightly coloured little capsules, each with a ball bearing inside, and when you placed one on a flat surface and tilted it, the “bean” did amazing acrobatic tricks.

I didn’t know anything then about real jumping beans which come from Mexico.

Well, in November last year, while in Kruger National Park, Mrs Chiel and I discovered our own domestic brand of the real thing and were totally amused and fascinated by what we saw.

It was on the same visit, same day and same place while having lunch at the Afsaal picnic site alongside the road between Skukuza and Malelane Gate, that we also “discovered” Fever-tree mosquito and fly repellent.

I wrote about that, just as the mozzie and fly season was getting into gear, and it has become quite popular here as a result.

Anyway, we were sitting at Afsaal in the shade of tamboti trees, ducking pesky flies before the repellent got rid of them, when movement on the ground caught my eye.

There lay thousands of small, dry seeds – in reality fruit – and they were moving.

Up, sideways, spinning ... doing all manner of amazing things. I couldn’t believe what I was seeing, gingerly picked up a few and placed them on the table for closer examination. In the hot sun they became even more active, bouncing, rolling about and falling off the table.

Mrs C and I were mesmerised, giggling like children, wondering what was inside the hard- shelled seeds to make them dance like that.

We put a handful of them, about 15 I suppose, inside a clear plastic sandwich box and carried them around with us in the car, showing them to anyone in the game reserve who was interested. Many were, watching as the seeds hopped and popped for no apparent reason.

It was only when we got back to Johannesburg that we were able to find out more about the strange phenomenon.

Apparently a small grey moth lays its eggs in the fruit and come summer, from about November to January, the fruit dries, falls to the ground, and a little white moth larva inside each seed (picture above) starts stretching and jackknifing, often with an audible click, that sends the seed spiralling about.

In addition to being called jumping beans, I’ve even found reference to “tree popcorn” which is also highly appropriate.

Tamboti wood was once prized for furniture manufacture but the trees are now protected. The tree exudes a white latex when cut and should never be used for cooking, heating or braaiing as the smoke is poisonous. That latex has also been used as a fish poison and in eras gone by, as poisonous tips on arrows.

The trees grow chiefly in northern KwaZulu- Natal, Swaziland and north-east South Africa. Strangely, Mexican jumping beans are also propelled by small moth larvae. — Chiel today is Robin Ross-Thompson; e-mail