We are spending our first Autumn our new home in Cornwall and have noticed that we have a lot of small spiders,many laying nests - mainly around our conservatory kitchen and around the doors and windows. The majority are outside but we have found a few indoors. We have a lot of friends with babies and small children that visit and often crawl around our kitchen floor. Just wanted to check if they are false widows or not? Thanks for any advice
The 2 spiders shown are false widows (Steatoda nobilis). If you have any reservations at all, then relocate them outside. I'd check under appliances in the kitchen, just to be sure. They don't usually like being at ground level, but if the property has been empty for any time...this is a possibility.
The spiders that are already outside are less likely to be an issue, as Winter comes they will withdraw into hiding places & hole-up until the Spring. Removing them from outside areas may be a massive task and one that you may have to repeat seasonally...in doing so, you may actually drive homeless spiders indoors, or risk bites.
Female S. nobilis are typically home-bodies, they don't roam around much. They also tend to make webs away from the floor...they may however end up in porches/around doorways/in conservatories. They aren't aggressive & are really quite skittish, usually fleeing when threatened.
Males (smaller abdomens) do wander more, but they are likely to be finished off over the Winter.
Even if the worst were to happen & someone received a bite, this is not dangerous. Those with reduced immunity/allergies should be careful, signs of infection (the bigger risk and common to any bite/sting) should be treated quickly with antibiotics.
I also wouldn't necessarily assume that all the spiders around your windows are false widows, Zygiella species are often mistaken for Steatodas, but they weave classic orb webs with 2 missing sectors and have brown heads with a thick dark stripe down it's length (Steatodas weave messy, irregular webs and tend to have more uniform colouring on the head). Zygiella also make little sacks of web that they often withdraw into. Zygiella are harmless and can live in close proximity with Steatodas & each other...Steatodas seem to like more space between adult females of the same species.
Thanks for your reply Mark - really interesting and helpful. Most of the spiders I have seen have a similar distinctive white markings on their backs, some are larger than others. The ones in the kitchen are quite high and tend to spin the webs across our glassed roof - although I have found them on the window sills too. I will remove the onces indoors as my 3 year old niece has serious allergies. We have a lot outside - visably about 20- 30 around the outside of the kitchen and many more around our garage. Should we be concerned about the numbers and the fact that there are a fair few visable egg sacks? Thanks for your reply, much appreicated Katie
It does sound like you have rather a lot of them. It still maybe useful to have some pics of the smaller ones, just to be sure?
Removing any that you can get to easily may be a good idea, but removing them completely will be difficult. Even if the eggs hatch, the spiderlings will likely disperse when still very small, so I think it unlikely that you will suddenly see a population boom of adults.
These last 3 photos all show Zygiella species (likely Z. x-notata), missing sector orb weavers. If you look at their webs carefully you'll see that they are the classic orb web, but may have 2 sectors missing the concentric rungs? False widows don't make webs like this.
False widows & Zygiella may live close to each other & appear similar at a glance...I see both every day & can still be caught out on occasion.
Steatoda nobilis make more of a hammock, or shelf-like web that they often patrol hanging upside down (dorsal side to the floor, belly up).