The 1 quart bag of Zoo Med Creatures Creature Floor is a 100% natural cypress mulch substrate designed specifically for the sensitive needs of insects, spiders and other similar invertebrates. The pet safe mulch provides your creepy crawly critters with an environment that is incredibly similar to their natural habitats in the wild. Additionally, the mulch helps to hold humidity, which is an essential component in a successful terrarium. It helps to gently mist the substrate periodically to raise humidity levels within the tank. For more accuracy and to monitor humidity levels, use this product in conjunction with a thermometer or humidity gauge.