Rat Fleas (Xenopsylla cheopis)
Rat fleas are parasites that feed on the blood of rodents. They start as eggs and hatch on the ground or in the nest or nesting material of the animal. When the eggs hatch, the larvae or between 3 and 5 millimeters long and resemble tiny, legless worms. In the larval stage, they eat flea drippings, dead skin cells, and animal hair. Once the larvae have reached the appropriate size, they will spin themselves into a cocoon in order to pupate. Once they emerge from this pupae stage (which occurs within the cocoon), they will then be able to feed on blood and reproduce.
The mouth of an adult rat flea is able to inject saliva and draw blood. They do have two eyes, but those eyes are only able to register light. They are also able to jump 200 times their body length, and 130 times their height. These parasites are known to carry a huge range of diseases that they contract from the rats they feed on. It has long been known that they are the main cause of a bubonic plague infection. These diseases can be spread to humans after the flea bites an infected rat and then bites a person.