Springtails do not need light to survive, grow, or reproduce. In fact, they actively avoid it. When given a choice between light and darkness in lab experiments, over 77% of springtails consistently moved toward the dark side. Many species spend their entire lives deep in soil or inside caves without ever encountering sunlight. That said, a basic day/night cycle appears to benefit captive colonies, even if the light itself isn’t something springtails seek out.
Springtails Actively Avoid Light
Springtails are negatively phototactic, meaning they detect light and move away from it. A study published in the Journal of Insect Science tested three different species and found strong, consistent light avoidance. Over 77% preferred darkness over white light, and over 69% preferred darkness over ultraviolet light. When forced to choose between white light and UV, more than 76% moved toward the white light, suggesting UV is especially aversive to them. These animals are built for cool, dark, moist habitats, and their behavior reflects that.
This isn’t surprising when you consider where springtails live in the wild. They thrive in leaf litter, under bark, in the top layers of soil, and inside caves. Some species live so deep underground that they’ve lost their eyes entirely over evolutionary time. Cave-dwelling and deep-soil springtails typically have no visible eye structures at all, and several of these species reproduce without mating through a process called parthenogenesis. Light plays no role in their life cycle.
How Springtails Detect Light Without True Eyes
Springtail vision varies dramatically between species. Some have relatively complex arrangements, with up to eight simple eye units on each side of the head. Others have just one per side. And some, like the commonly cultured species Folsomia candida, have no external eye structures whatsoever. Yet even this “eyeless” species still detects and avoids both UV and white light just as reliably as its sighted relatives.
Researchers believe Folsomia candida may have internal photoreceptors, structures beneath the surface that sense light without a visible lens. This would explain how a species with no detectable eyes still responds to light with the same strong avoidance behavior. Other species use light in more sophisticated ways. One species appears to gauge the angle of the sun before jumping across open ground, possibly detecting polarized light to navigate. So while springtails don’t need light, many can sense it and use that information, mostly to stay out of it.
UV Light Can Harm Springtails
Springtails don’t just dislike light. Ultraviolet radiation is genuinely dangerous to them. A review of UV effects on small arthropods found that direct exposure to UV light delays development, reduces survival rates, and impairs normal behavior. Immature springtails are more sensitive than adults, making UV exposure particularly risky for breeding colonies. This is consistent with the lab findings showing that UV light is the type springtails avoid most strongly when given a choice.
For anyone keeping springtails, this means direct sunlight or UV-emitting bulbs positioned close to a colony can do real damage. Even if adult springtails survive the exposure, their young may develop more slowly or die off at higher rates.
Lighting for Captive Springtail Colonies
If you’re culturing springtails for a bioactive terrarium or as feeders, you don’t need to provide any special lighting. Springtails will breed and thrive in a dark closet. However, experienced keepers note that colonies seem to benefit from ambient room lighting on a normal day/night schedule. The springtails don’t need the light directly, but a consistent light cycle may help regulate their activity patterns in much the same way it does for other small soil organisms.
The practical guidelines are straightforward. Keep your colony out of direct sunlight and away from UV-producing bulbs. Normal room lighting, or the indirect light from a nearby terrarium lamp, is more than sufficient. If your colony is housed inside a vivarium with plants that need a light cycle, the springtails will simply retreat into the substrate during lit hours and come out when conditions are darker and more humid. This is exactly what they do in nature.
Temperature and moisture matter far more than lighting. Springtails need consistently damp conditions and moderate temperatures. If your colony is declining, the issue is almost certainly humidity, ventilation, or food supply rather than anything related to light.