Violin spider bites

back to Spider bites; back to Loxosceles

Loxosceles, the Violin spider with Sicarius, Six-eyed sand spiders, constitute the tropical to subtropical family Sicariidae. The spiders in this family have a virulent cytotoxic venom and one death did occur in South America from a bite by Loxosceles laeta a species not found in Africa. The venom is stronger than that of Sac spiders.

Loxosceles sp. (Violin spider). [image N. Larsen ©]

The name Loxosceles relates to the slanted fashion in which the legs are held with various colloquial names in use; Violin spiders and Fiddle backs relating to the violin shape marking on the carapace of some species; also called Recluse and Brown spiders. The three latter names are in use in America.

Violin spiders are those spiders most surrounded by myths and hoax emails. In 2003 an email made its debut in America about these spiders invading highly populated areas causing mass hysteria. An image of the American Brown recluse spider, Loxosceles reclusa, was included with a disturbing sequence of images of a hand with severely ulcerated thumb which is not proven to be a spider bite at all. This email did a world tour including a few circuits of South Africa warning of invasions of the Western Cape and Gauteng and pending danger and possible death. Unfortunately this email was inadvertently also forwarded by ignorant office workers from environmental, health, National Parks and conservation bodies as well as the local press.

Rick Vetter, University of California, has extensively researched all cases in the United States and has continued an endless crusade refuting the myth about Loxosceles reclusa bites. In the highly populated coastal California 700 cases of recluse spider bites were diagnosed annually yet only 15 specimens have been collected in the last 40 years. Truly cases of translocations. He also reports in the mid west of America where the synanthropic Loxosceles reclusa is very common, with students collecting 60 spiders, even collecting them by hand, without a single bite. In an old 1850s house 2055 recluse spiders were collected over a period of 6 months and none of the inhabitants were ever bitten. Subsequently the mother, after residing in the house for over 8 years was bitten on the finger while reaching into the basket of clothes ready for ironing without any serious envenomation. In southern Africa there are more than 10 species of Loxosceles, but they are fairly uncommon except for the Witwatersrand, Gauteng, where the synanthropic Loxosceles parrami occurs, although bites are rare.

Loxoscelism is the term used for envenomation by these spiders. It is important to note that, as with the sac spiders, necrotic lesions by Violin spiders are self limiting and heal spontaneously without medical intervention when kept clean to prevent secondary infection.

Violin spider bites normally occur at night and are not felt as the tiny fangs only just penetrate the skin. No visible bite mark is present. Slight swelling and redness (oedema and erythema) is evident after 2 hours, the central area may have a purple discolouration and can spread to 20mm in the next 6-8 hours at which stage it is painful. A blister usually develops at 2-3 days, collapsing at 10 days leaving a necrotic crater-like lesion 20-100mm in diameter. The lesion is now susceptible to infection but spontaneously starts healing a process that can take a few months and may require cosmetic surgery. The milk tart appearance normally result in doctors operating to remove the necrosis but this is actually the lesion healing as can be seen in the photographic images.
Treatment and the differential diagnosis are as for Sac spider bites.

Text by Norman Larsen ©