Story and photos by John O’Sullivan

A Cave spider; Meta-bourneti. It lives in the old furnace chamber beneath St Denis’ church and is quite harmless to humans – but not slugs. All photos: John O’Sullivan.

Under St Denis’ church something deadly lurks.  Well, deadly if you are an insect or a slug.

This is the Cave spider (Meta bourneti to specialists), which is quite harmless to other locals, including ourselves; nationally, this is an uncommon species.

In fact, we have been able to help it – and the tiny chamber under St Denis’ is just to its liking.

Our spiders were introduced to their man-made ‘cave’ in 2006.  Rob Mungovan, at the time South Cambs District Council’s Ecology Officer, needed to find a good home for a population discovered in an old air raid shelter near Papworth Hospital which was being demolished for development.

Putting them beneath St Denis’, which sits in its own Local Nature Reserve, looked ideal – and so it has proved, with the introduced population thriving and keeping up their numbers, with interested, and knowledgeable, villagers continuing to monitor them.

Despite a leg-span of 5 cm, the adult spiders don’t move around much.  They stay in the dark and await their prey.  Males are the same colour as the females, but slimmer and smaller and take no part in guarding the egg sac.

When well-fed, the adult female lays her many eggs in a round white ball of silk that hangs from the wall or roof of the cellar, looking like a miniature ping-pong ball.  The young spiders hatch into a world full of threats; the mortality rate of young is very high – as in all spiders.  The carrying capacity of the site is limited by territoriality, itself limited by factors such as prey availability.

A visit to the St Denis’ colony on 21st June 2020 revealed some 12 adult female spiders and half-a-dozen egg sacs.  The photographs below were taken on the same day.

A Cave spider with an egg sac.

Cave spiders have a leg-span of 5 cm.

A female Cave spider in her web.

A Cave spider with beetle prey.

So next time you pass through the churchyard, give our special spider a thought, and reflect that Hatley is doing its bit to help them.

NB  Their home, in what was once the furnace chamber for the stove in the church, is kept locked.

_{Post created 10th September 2020.}