Fleas are small (2-3 millimetre/0.08-0.1-inch) red-brown wingless insects that feed on the blood of mammals and birds. They are compressed side to side so that they can move through fur and feathers easily and have long legs that let them jump 100 times their height. They can survive for months without food and their young can live in our carpets and bedding. Flea bites are itchy and can cause allergic reactions. Fleas can also carry diseases such as bubonic plague and myxomatosis.
Answered by Kate Sherburn, Manchester Museum.