How to Expose a Butterfly Larvae to Different Wavelengths of Light to Change Its Color

Prepare your aquarium before the butterfly or moth eggs have hatched. This includes filling it with a little dirt and making sure the sticks they crawl around on go from dirt to mesh top. Research and gather the appropriate host plants for the larvae to eat. These will have to be fresh, as caterpillars will not eat dry or dead foliage. To be fully in control of what light waves reach the caterpillars, place the aquarium habitat away from direct sunlight (but not in a closet), and cover one long side with paper (the same color as the light used). This will heighten the effects of the wavelengths, especially since caterpillars (and adults) tend to become the color of their background as a defense mechanism.

Set up your lamp with a non-white bulb once the hatched caterpillars are inside their new home and the mesh is on securely. As white light is all colors, choose only one color to begin. For example, red. Shine the red light (or lights if you choose to have two lamps on opposite sides of the aquarium) into the habitat so the wavelengths will affect the larvae.

Mist the inside of the habitat occasionally to keep the humidity up. Caterpillars like a slightly higher humidity during their growth, and once they pupate they will require high humidity in order to hatch. Make sure the bottom of the aquarium is cleaned daily to prevent illness and mold, and change out the host plant daily.

Change the light (and the paper on the side) to another color once the caterpillars show signs of their first molt. This will alter the wavelengths affecting them and should help them become a different color for their next molt. Take photos if desired. Compare their colors with the same type of caterpillar in the wild. Butterfly larvae will molt more than once during their weeks spent in that stage. Each species has a slightly different time length spent as a caterpillar, so make sure you know beforehand what to expect.