Butterfly zoos are open to the public. A double-entry door is usually used to ensure that no butterflies escape.Exploration of such zoos may be with a guide or on one’s own, at leisure. Guided tours may last about fifteen minutes, as the guide points out all the species of butterflies that are in the greenhouse that day (new shipments usually arrive weekly, and stocks vary). Guides may also show butterfly eggs, caterpillars, and chrysalids and identify specific plants that are favored by each species. Between 10 a.m. and 1 p.m. is usually the best time to see butterflies emerging from their pupae.