On 30 December 1,200 butterfly cocoons arrived at The Glasshouse at RHS Garden Wisley in a surprisingly small box. Now the time has come for them to spread their wings
In preparation for their arrival we’d turned up the heating in the teaching lab and damped down the floors - a very warm, moist environment is essential for their proper development.
These gorgeous creatures need space to open their wings, once the time is right, so they need to be hung upside down, about an inch apart. We stuck the pupae with glue onto bamboo canes and balanced them on a frame in the puparium. As the butterflies inside the cocoons started to wake up, warmed by our hands, their abdomens wriggled, which made sticking them tricky and a little weird!
Pupae come in variety of different shapes: many are camouflaged to look like curled leaves, others are brightly coloured, some are even gold and these signal to other animals that they are poisonous. In the UK, our butterflies tend to flit about hurriedly because they are vulnerable to predators; many tropical butterflies, however, drift slowly, unafraid of being eaten, because they have poisons from tropical flowers such as Passiflora
How? By eating them when they’re still caterpillars. These plants use toxins as a defence mechanism to deter insects, but some caterpillars are one step ahead in the arms race and have evolved ways of consuming the toxins and storing them without being harmed.
Once the butterflies emerge we carry them out of the puparium to the feeding tables. They are surprisingly clingy and grip onto our fingers. The feeding stations contain sugar-water and pieces of rotting fruit, and we also add a few flowers that contain nectar to the display, ideal for butterflies to feed on. In the life cycle of a butterfly, the caterpillar is the stage that consumes the solid food, bulking up, then a cocoon forms and the caterpillar liquefies inside (euwww!) before re-forming into a butterfly. The butterfly stage consumes no solid food at all. Those that drink only nectar and sugar-water, live for the least amount of time but butterflies that feast on fruit - and even, in the wild, the juices of rotting meat - can live for longer.
When looking for somewhere to lay eggs, the butterflies respond to reflective surfaces, preferring shiny, smooth leaves to rough ones. However, this is the stage we want to avoid in The Glasshouse. Hungry caterpillars can devour a banana leaf in a few days, and if the butterflies stayed all year round we would have no plants left at all – not ideal! So as the butterflies lay their eggs, we do frequent leaf checks (Musa
are most at risk) removing the eggs (and caterpillars if they’ve hatched) and sending them back to the butterfly farm.
We really love having these tropical butterflies in The Glasshouse. On sunny days they’re especially active, so please come along and enjoy them with us. Check out the Butterflies in the glasshouse
page for more information.