This bat preys on larger insects, mainly beetles, which they hunt for about four to five hours after emerging late in the evening. They are known to forage on the ground for some of their insect prey. Male greater mouse-eared bats are polygamous, and may have a harem of up to five females. The females form large maternity roosts in attics or caves and give birth to one offspring, usually in June. When they leave to feed, females leave their babies in a crèche and there are often several females left to guard the roost. The young bats can fly after three weeks, and become sexually mature at three months.