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Thursday, 31 December 2009

Butterflies of Bristol 12: How does it work?

Butterfly houses are becoming increasingly popular all over the world, and can have a significant economic effect in the source countries for those involved on the butterfly farms, so I thought it would be a good idea to end this series, and the year, with some facts and opinions of my own about them.

The reason for their popularity is not hard to find – butterflies are beautiful, harmless (although I have seen a few people jump when a Morpho or Owl butterfly lands on them!) and comparatively easy to maintain. Basically any enclosed space can be used to house butterflies (our Butterfly House is basically a poly tunnel), provided that the internal environment is kept within the correct parameters. For tropical butterflies, this is an air temperature with a minimum of 25 degrees Celsius during the day, preferably higher, and a night temperature of at least 15. Humidity is the other important variable – for butterflies from rainforest areas it should be a minimum of 70%. Low humidity results in poor emergence, damaged wings, and shortened lifespans. Some butterflies will still fly in low light levels, especially Glasswings and Owl butterflies, but most need maximum illumination. Our butterfly house has supplementary lighting which extends the photoperiod in the winter months.

All this takes energy of course, so the carbon footprint of a Butterfly house can be high. Heating in our House is by a biomass fuelled boiler, which means that most of the energy required to run the house is carbon-neutral.

Once the butterflies have emerged, they require feeding. Nectar is provided by flowering plants (Lantana and Pentas are particularly useful), and also by vials of 5% fructose solution in vials on feeding tables. The artificial nectar is changed daily so that the sugar solution does not ferment. Fruit is laid out on separate tables for the fruit feeding species like Owl butterflies, Morphos, and Charaxes.

Many butterflies will mate in a butterfly house, but raising larvae away from the native countries is very labour intensive, However, Passiflora, Banana, and Citrus plants are seen in most Butterfly Houses as part of the planting displays, and the butterflies will oviposit on these. This makes control of the larvae numbers very important, as otherwise plants will quickly be stripped bare of leaves and die. We usually keep Passiflora plants in pots, which means that we can change them around to give the plants a rest.

An often overlooked aspect of running a butterfly house is pest control. Obviously insecticides cannot be used, so a variety of biological controls are used to protect the plants. The other main threats are spiders, which will feed on the adult butterflies, and parasitic wasps, which will attack the larvae (they often emerge from pupae after developing inside the larva, which is why you see pupae being kept in an enclosed space to emerge in most butterfly houses).

Finally, the big question – how do we get hold of the pupae? They are supplied by butterfly farms in the tropics all over the world, where local farmers will raise them to the pupa stage and then ship them to butterfly houses all over the world. We have two suppliers – Kipepeo in Kenya and El Bosque Nuevo in Costa Rica. Some butterfly houses, obtain theirs via importers, which in the UK are London Pupae Supplies (they also operate in the US), and Stratford Butterfly Farm. If you want to have a look at them, here are the links:

Kipepeo Butterfly project: http://www.kipepeo.org/

El Bosque Nuevo: http://www.elbosquenuevo.org/

London Pupae Supplies http://www.oxfly.co.uk/

Stratford Butterfly farm: http://www.butterflyfarm.co.uk/

Many people after visiting a butterfly house may have wondered if they could do the same thing at home. I hope from the above you may have some idea of the work involved, but it is entirely possible for a keen gardener for example to convert a greenhouse – they could still use it for their plants as well. To keep heating costs down it could for example only house butterflies during the summer months. Important points to remember are making sure it is escape proof and controlling spiders in particular. For further reading I suggest you try and get hold of The Butterfly gardener by Miriam Rothschild and Clive Farrell, which has a lot of useful information.

Well, that’s about all for this year. Coming up in 2010 I will be doing posts on the animals and plants we have at Bristol, news and updates of campaigns we are involved in, and reports from the Research Colloquiums we have each month (check the Bristol Zoo website for details of these).

Happy New Year!

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