Your science questions answered: ‘Why are spiders leaving a mess on my front door?’

The science team at Spoofflé often receive technical queries from readers around the world, so we have decided to start publishing these for the benefit of our many thousands of followers, together with our explanations. Sort of an ‘Ask Spoofflé’ column that will appear from time to time.

Today’s email is from Adrian Stewbald, who lives in Crankerton-under-Wold, Shropshire.

Adrian wrote:

“Dear Spoofflé,

A spider has taken up residence on my front door. Not content with weaving a web that catches me full in the face whenever I use the door (and I know it gets pissed off when I wreck the web with my face because they make a new one by the time I return) he or she is also making a mess down the door itself. How can something so small create so much of the stuff? Or is it fear from the spider’s victims that is causing the mess? Cheers, Adrian”

We asked Spoofflé’s Science Editor, Dr Oliver Flimwell, to reply.

“Hi Adrian,

You are not the first person to remark on the unexpected presence of spider faeces in their webs. I hope I can spread some light on the phenomenon you have witnessed since it fits very closely with my own experiences.

During the early 80’s I was a junior biologist at the Lawrence Mitchell Centre for Insect Research, just outside Crawley. As part of our government-funded activities, we investigated the mating activities of a range of metazoa including the male purseweb and wolf spiders. This obviously required us to bring together males and females of each species in a controlled manner, in order to achieve reliable results. Apart from monitoring the heart rate, body temperature and erectile distension of the males using 2 micron probes glued to their bodies, we also monitored the faecal deposits passing from the anal tubercle.

Imagine my excitement one evening when, whilst watching a particularly aroused male dancing around a disinterested female (displaying extreme chleroptoma on its rear legs) I noticed faecal deposits arriving in direct proportion to his enthusiasm. I too became extremely excited (although not that excited) since this had never been witnessed before.

My findings were eventually published in the New Scientist (January 1987). Effectively, the male was pooing himself with excitement. What you found outside your door was evidence of a passionate evening between a male and quite possibly a dozen females, who we later noted, are able to control their anal sphincter.”


Editor’s note: Please send Spoofflé your science questions, for the attention of Dr Oliver Flimwell.