What characteristic is notable about fleas?

Fleas are noted for their characteristic of feeding on the blood of mammals and birds. This feeding behavior is essential for their reproduction and survival, as they require nutrients from the blood to develop from larvae to adult fleas. Fleas are ectoparasites, meaning they live on the outside of their hosts and can infest a wide variety of animals, including pets like dogs and cats and humans.

The other characteristics mentioned do not apply to fleas. For instance, fleas are not winged insects; they lack wings altogether but have powerful hind legs that allow them to jump significant distances relative to their size. They also do not primarily live in soil; instead, they inhabit areas close to their hosts, such as carpets, bedding, and pet fur. Additionally, while flea activity can peak during warmer months, they can be present year-round in indoor environments. This adaptability enables them to survive in various conditions, challenging the notion that they only appear in summer.