light levels

Roger C. KENDRICK kendrick at
Sat Sep 26 14:21:14 EDT 1998

Martin Jewiss, Stratford-upon-Avon Butterfly Farm. wrote:

> Can anyone point me in the direction of literature and/or research on
> levels (lux) of artificial light required by tropical butterflies in order
> to fly.  I know there different requirements between species, I'm looking
> for info. concerning Papilionidae (eg Papilio spp., Graphium spp.);
> Nymphalids (eg Hypolimnas spp., Precis spp., Charaxes spp., Hamadryas
> spp.); Danaus spp.; Caligo spp.;  Heliconidae etc.
> I'm also wondering if in addition to intensity, there are wavelength
> requirements.
> Any help, advice, info. greatfully appreciated.
> Thanks
> Martin Jewiss.
> Stratford-upon-Avon Butterfly Farm.

 Hi Martin,

I can't help with specific lux levels, but I use the approximate equivalent
(relevent to the following discussion)

   * strong sunlight:  > 50,000 lux (the kind of light that makes you squint
     without sunglasses)
   * normal sunlight:  25,000 to 50,000 lux
   * hazy or thin cloud cover: 15,000 to 25,000 lux
   * heavy cloud cover or under woodland canopy (above shrubs) in normal
     sunlight: 5,000 to 15,000 lux,
   * dark skies (rain imminent) or on woodland floor in normal sunlight: 1,000
     to 5,000 lux.

Here in Hong Kong, I have seen Graphium (sarpedon & agamemnon) active in light
rain, probably < 5,000 lux.
Most Papilio spp. here will also fly in poor light.
Precis and Charaxes will normally fly in sunny conditions; I've not seen them
active in the evenings or when cloudy.
The danaids here are active from before sunrise until dusk and in very cloudy
condtions - right throught the range of light levels above. I don't see much of
the Hypolimnas spp, but they've always been in strong sunshine.

I don't know about light wavelength requirements, but I'd guess that trying to
reproduce natural sunlight would need a mixture of tungsten and fluorescent
(white) lights for a close approximation.

Hope this helps, even though it's somewhat anecdotal observation.



Roger C. KENDRICK   B.Sc.(Hons.)
PhD student & Demonstrator, Dept of Ecology & Biodiversity
The University of Hong Kong
mailto:kendrick at   « Hong Kong Moths »   « H.K. Lepidoptera Group »
mail: Kadoorie Agricultural Research Centre
      The University of Hong Kong
      Lam Kam Road, Shek Kong,
      Yuen Long, New Territories
      Hong Kong
fax: (852) 24885285

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