ULTRAVIOLET LIGHT FOR CAPTIVE REPTILES 

      Lizards, turtles and probably other reptiles need natural sunlight for good health.  Ultraviolet rays are especially important for Vitamin D synthesis and calcium metabolism.  UV rays do not penetrate window glass, so animals placed in a sunny window receive no benefit other than heat.  Neither incandescent nor cool white fluorescent tubes provide UV rays, making then unsuitable light sources for species that require UV. 

Sources of UV Light:

      1) Sunlight - The current consensus of herpetoculturists is that no artificial source of UV light is as good as the sun, especially in iguanas, chameleons and turtles.  If at all possible, lizards and turtles should be exposed to natural, unfiltered sunlight as often as possible.  We advise owners to place these animals outside on sunny days over 70^oF (20^oC).  Escape proof and predator proof cages should be constructed from treated wood and heave gauge screen or hardware cloth.  Turtles may be placed in concrete mixing tubs, children's swimming pools or outdoor pens.  Glass - even a glass aquarium with a screen top - should never be used when providing access to sunlight because it will trap heat (greenhouse effect) and filter out UV rays.  An area of shade and access to water are necessary to prevent overheating.  Cages must have secure bottoms or be buried deep enough with a layer of stone next to the wall to prevent lizards and turtles from tunneling to freedom.  Be aware that lizards which are docile and slow indoors may become extremely quick and aggressive after a few minutes in natural sunlight.  Care should be taken to avoid escape - one might take off too quickly to catch - or attack.  Screened porches or open, screened windows facing east or south allow access to sunlight for lizards kept indoors.  It is my belief that exposure to natural sunlight as often as possible is crucial to the health and well being of lizards and turtles.  Even three months of sunlight in the summer will boost a reptile enough to survive the other nine months indoors with artificial UV sources. 

      2) Vita-Lite or similar full spectrum fluorescent tubes - Full spectrum light mimics natural sunlight.  Little heat is given off so other heat sources are required.  It has been reported that the UV light emission from these tubes deteriorates before visible light and that Vita-Lite tubes should be replaced every 6 months to insure adequate UV production.  Vita-Lites should be within 24 inches of the reptile and not be filtered by glass or plastic. 

      3) Black Light Fluorescent Tubes - These should not be confused with black light blue (B.L.B.) tubes used for lighting fluorescent minerals, posters, and psychedelic paraphernalia.  Black light tubes such as General Electric F20T12 (20 watts, 24 inches long) or Sylvania F40BL (40 watts, 48 inches long) may be ordered from electrical supply distributors.  Again the tube should be within 24 inches of the reptile with no glass or plastic filters over the light. 

It is common for reptile keepers to use a two-tube fixture with one black light and one Vita-Lite.  This is the best arrangement but if only one can be afforded, choose the Vita-Lite. 

Plant lights or other wide spectrum lights are insufficient for maintaining reptiles. 

The best situation is to have the UV source within the cage but set up so that the reptile cannot get too close and burn itself, or through a screen.

REMEMBER: THERE IS NO SUBSTITUTE FOR NATURAL LIGHT

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