Gerald Durrell, Encounters with animal, Londres, Penguin, 1958.

One of my first experiences with animal architects was when I was about ten years old. At that time I was extremelt interested in freshwater biology and used to spend most of my spare time dredging about in ponds and streams, catching the minute fauna that lived there and keeping them in large jamjars in my bedroom. Among other things, I had one jam- jar full of cadds larvae. These curious caterpillar-like creatures encase themselves in a sort of silken cocoon with one end open, and then decorate the outside of the cocoon with whatever materials they think will produce the best camouflage. The caddis I had were rather dull, for I had caught them in a very stagnant pool, They had merely decorated the outside of their cocoons with little bits of dead water-plant.
I had ben told, however,, that if you remove a caddis larva from its cocoon and place it in a jar of clean water, it would spin itself a new cocoon and decorate the outside with whatever materials you cared to supply. I was a bit sceptical about this, but decided to experiment. I took four of my caddis larvae and very carefully removed them, wriggling indignantly from their cocoons. Then I placed them in a jar of clean water and lined the bottom of the jar with a handful of tiny bleached seashells. To my astonishment and delight the creatures did exactly what my friend said they would do, and by the time the larvae had finished the new cocoons were like a filigree of seashells.
I was so enthusiastic about this that I gave the poor creatures a rather hectic time of it. Every now and then I would force them to manufacture new cocoons decorated with more and more improbable substances. The climax came with my discovery that by moving the larvae ti a new jar with a new substance at the bottom when they were half-way through building operations, you could get them to build a particoloured cocoon. Some of the results I got were very odd. There was one, for example, who had half his cocoon magnificently arrayed in seashells and the other half in bits of charcoal. My greatest triumph, however, lay in forcing three of them to decorate their cocons with fragments of blue glass, red brick and white seashells. Moreover, the materials were put on in stripes-rather uneven stripes, I grant you, but stripes nevertheless.
Since then I have had a lot of animals of which I have been proud, but I never remember feeling quite the same sort of satisfaction as I did when I used to show off my red, white and blue caddis larvae to my friends. I thonk the poor creatures were really rather relieved when they could hatch out and fly away and forget about the problems of cocoon building

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