In the wild, common house geckos, which are indigenous to southeast Asia but have become invasive species in the United States, Australia, and parts of South America and Africa, eat various types of insects and spiders. Mediterranean house geckos, which have also spread around the world from their native habitats bordering the Mediterranean Sea, prey on moths, roaches and other insects.
Because the common house gecko is native to the tropics, it thrives in hot, moist climates. It frequents rotting wood in search of the insects it preys upon. On the other hand, the Mediterranean house gecko is attracted to lights on houses where at night it preys upon the creatures drawn to the lights.
In captivity, either species of house gecko can be fed fruit flies, silkworms, mealworms and crickets. Before being fed to house geckos, crickets should be gut-loaded, or fed nutritious food, and also dusted a few times a week with a calcium supplement and once a week with a multivitamin supplement. Young geckos should be fed every day, but adults can usually be fed every other day. The amount can be judged by how much they eagerly consume. Besides the food, they should have clean water daily, and ideally, their habitat should be humidified with regular misting.