Largest flea

Siphonapterologists recognize 1830 species, of which the largest known is Hystrichopsylla schefferi, which was described from a single specimen taken from the nest of a mountain beaver (Aplodontia rufa) - a peculiar species of North American rodent inappropriately referred to as the mountain beaver, as it is neither a mountain-dweller nor a beaver - at Puyallup, Washington, USA in 1913. Females were measured up to 8 mm (0.3 in) long - roughly the diameter of a pencil. 

The common flea (Pulex irritans) has an average length of 1-2.5 mm (0.04-1 in)

 

Fleas on average live for 2-3 months. Immediately after take off, the velocity of an average flea is around 1ms