Brightworms

Brightworms are actually a variety of caterpillar that are native to the Free City, one of the few native species of the demi-plane. They are covered in luminescent dots that form two rows down their backs, and they produce a bioluminescent silk that glows brightly enough to provide dim illumination in a 10x10 foot area. The silk will glow brightly enough at this level for approximately one week, after which it is typically discarded, or woven into garments or accessories. Older, more mature worms produce more silk. 
Wild brightworms live  approximately 5 years, though specimens kept in captivity have lived 20 years or more.

Basic Information

Genetics and Reproduction

Fully grown Brightworms can lay up to 100 eggs at a time. They can reproduce asexually via parthenogenesis.  However, they are hermaphrodites, and can reproduce sexually in the presence of of other Brightworms.

Growth Rate & Stages

They exhibit a form of Neoteny, where they stay in their juvenile caterpillar form for their entire lives, and seem to have lost the ability to fully form cocoons, inside which they could progress to the fully adult version of the species.
They hatch from eggs into brightworm larvae, which are typically 5 mm - 12 mm in length. After about a year, they grow and mature into full, adult brightworms.
Adult brightworms are 15 -20 cm in length, but they never technically stop growing. Very old specimens have been known to reach almost 60 cm.

Ecology and Habitats

Brightworms are attracted to light, and will congregate in any brightly lit space, and it is theorized that this helps them to find other brightworms. However, a brightworm kept in the dark will produce more silk, though this can be stressful for the worms and ultimately shorten their lifespans. Most brightworm farmers agree that a level of dim illumination is best for keeping the animals happy and producing silk.

Dietary Needs and Habits

Brightworms will eat almost any organic material, however for optimal light production, a diet high in certain phosphates and other mineral components is recommended. Most farmers supplement their feed with a high percentage of bone meal, guano, and mushroom compost.