False widow spiders

 

 

What should you do if False Widow Spiders are found on your premises?

There are over 650 species of spider known to live in the UK. The vast majority are beneficial, harmless to humans, helping to keep flies in check.

However, there are a few that have gained notoriety through the press (see links below) and the significant impact they can have upon those working / using buildings in which they are found. This is because they deliver a very painful bite which depending on the reaction of the person bitten may be similar to a wasp sting (pain or possibly an anaphylactic response).

These spiders are known as False Widow Spiders. Their name derives from the fact that they are commonly mistaken for the infamous, black widow spiders which belong to a different genus Lactrodectus and have a red hour glass marking on their abdomen. Six false widow spider species live permanently in UK, however the three most common false widows are the “rabbit hutch spider” (Steatoda bipunctata), the “cupboard spider” (Steatoda grossa) and the “noble false widow” (Steatoda nobilis).

They are most often associated with dark, sheltered areas in buildings and gardens. The “Rabbit Hutch Spider”, Steatoda bipunctata, is a relatively small spider, with a body length being 10-15mm (female) and only 3-6mm (male). It is shiny, black and globular with two dents in its abdomen. It spins a loose tangle of webbing, with a tube of silk in one corner that leads into a crevice where the spider hides in the day. This web is often at least 1.5-2m above ground level, and sometimes higher.

The “Cupboard Spider”, Steatoda grossa, are similar in size and shape to the “Rabbit Hutch Spider” with the male generally being smaller in size. They are typically brown to black with some white markings and can live for up to 6 years (although the male will die after mating so often lasts only 1 – 1.5 years).

Noble false widows, Steatoda nobilis, have a distinctive cream ‘skull-shaped’ marking and are brown with reddish-orangey legs. The spiders increase in numbers during warmer months, but in late summer and autumn they may become particularly conspicuous as the males wander more extensively in search of a mate. As a consequence, reports of false widow spiders tend to peak in October.

They are most commonly reported within schools, universities and hospitals where they obviously cause disruption

What should you do if False Widow Spiders are found on your premises?

Carry out a risk assessment and attempt to mitigate any identified risks.

Although false widows are venomous, the venom is not particularly potent. Generally, the bite symptoms are localised pain, minor swelling, nausea or lethargy. There have been no reported deaths, coma or permanent injury from its bite in the UK BUT there have been isolated cases of people needing hospital treatment after being bitten, in most case due to an allergic reaction to the spider’s venom.

Cleaning in the correct areas

Regular cleaning denies potential food sources for the spider, as well as removing webs and/or spiders from outside of buildings. Gloves should be worn when cleaning.

Remove Harbourages

Sealing potential harbourage points in risk areas, may reduce the chance of spider ingress and consequently reduce contact with the spiders.

Treatment

Spiders are susceptible to insecticides. When applied in targeted areas, these treatments can be very effective

In the news

https://www.bbc.co.uk/news/uk-england-gloucestershire-24623652

 

© Rokill Ltd. 2019 All Rights Reserved.
Website designed and developed by Farrows