However, they are still objectionable because of the bites they inflict and the deep-rooted social stigma attached to humans with flea infestations. Occasionally psychological problems arise with the induction of delusory parasitosis, in which the victim imagines he is infested with ectoparasites. Flea bites are identified as a tiny dark red spot surrounded by a reddened area. The bite persists for one or two days and is intensely irritating. First bites are not generally liable to cause serious reactions, hut they may lead to hypersensitivity which will make subsequent bites troublesome.
Some people develop immunity to flea bites whilst others are naturally immune.
They are sticky and readily adhere to the substrate. Four to eight eggs are laid after each blood meal and a single female may produce 800 - 1000 eggs during her lifetime, which may be as long as two years. The eggs hatch in about one week to give white, threadlike, legless larvae 1.5mm long. The larvae thrive in dark, humid places such as animal bedding and carpet fluff and feed on organic debris and adult flea excrement. The latter forms a valuable part of the diet as a source of blood, which some larvae, while not attacking the host, require for their development.