The term 'Beagle Biter' is a nickname for a FLEA, which is an insect that feeds on the blood of mammals and birds. Fleas are known to be a nuisance to both humans and animals, and they can cause skin irritation and discomfort. Beagles are a type of small hound dog, and they are particularly prone to FLEA infestations. Therefore, the term 'Beagle Biter' is used to refer to a FLEA that is likely to bite a beagle.