Are they dangerous?
Fiddleback Spider (Loxoceles rufescens). Photo: G Millen © Australian Museum.
Black house spider (Badumna insignis). Photo: M Gray © Australian Museum.
White-tailed spider bites can cause initial burning pain followed by swelling and itchiness at the bitten area. Occasionally, skin weals and local blistering or ulceration have been reported - conditions known medically as necrotising arachnidism. As well as the spider's venom, secondary bacterial infection of the wound could be a contributory factor in some bites.
Other spiders have also been reported to be involved in cases of minor skin ulceration. They include the Brown House Spider Steatoda; the Black House Spider, Badumna insignis; the Slender Sac Spider, Cheiracanthium; and the introduced Fiddleback Spider, Loxosceles rufescens.
However, a debate continues about the involvement of white-tailed spider bite in cases of ulcerative skin lesions. Although patients with such symptoms are often diagnosed as probable white-tailed spider bite victims, typically there is no definite evidence of a spider bite being involved. Sensational media reporting of supposed cases of severe 'necrotising arachnidism' has given white-tailed spiders a bad reputation.
Against this often anecdotal evidence, a recent study has monitored the medical outcomes of more than 100 verified white-tailed spider bites and found not a single case of ulceration (confirming the results of an earlier study). The available evidence suggests that skin ulceration is a rare rather than a common outcome of white-tailed spider bite.
There are a number of well-documented causes of severe inflammatory skin lesions and ulceration, notably bacterial and fungal infections. Such secondary (or primary) infections may be the cause of ulcerative symptoms that have been attributed to white-tailed spider bites.
