Recommendations for attracting fireflies: Cut your grass only a couple of times a year. And because firefly larvae eat snails, slugs, and worms, anything that attracts these critters is good for the fireflies. These recommendations may not be suitable for an urban or suburban home site. However, having natural areas in your yard and reducing the use of outdoor lighting toxic chemicals may help bring them into your viewing area.
For more information read: The Gloworm.