A Note on Fleas and Rats with Reference to Plague in Calcutta

The rat flea is the intermediate host of the parasites of bubonic plague. Fleas are regarded as free parasites as they remain on the host generally during the time they feed. The flea passes through the egg, larval, pupal and adult stages and the whole life cycle covers roughly three weeks. The eggs are deposited in places where the host rests. For egg-laying, the female usually selects dark and dry places such as rubbish, debris and dust in domestic houses, under the carpet, in godowns and granaries, etc. Rat fleas often lay eggs in rat holes. Fleas of either sex live exclusively on blood which is