Every year around now, people notice an increase in spiders, both out in the countryside, in gardens, and even in their homes. From August until October, spider sightings peak. There are several reasons for this. One is that it is peak breeding season, and males come out of hiding, becoming more visible and active as they search for mates. Additionally, many spiders have been growing all summer and have finally reached their adult size. Along with their larger webs, they are therefore more obvious to the observer. Many people may fear spiders, but they have a significant role in the ecosystem, controlling unwanted flies and biting insects, and many have fascinating lifestyles and traits. If you take a closer look, you may discover a sense of appreciation instead of apprehension.

Spider facts

According to a checklist published last year, there are an astounding 423 species of spider living in Ireland. They may be found everywhere, from gardens, towns, and cities to the tops of mountains, shorelines, and, of course, even our homes. Spiders are diverse and adaptable and can be found on six of the seven continents. Despite forming a huge and significant part of our biodiversity, they are underappreciated and understudied. These eight-legged arachnids not only control pests, they are also important in the food chain and serve as prey for a large variety of species, including birds, amphibians, reptiles, and mammals. All spiders produce silk from spinnerets at their rear, but not all spiders use this to form webs. Other uses of the silk produced include building protective retreats, protecting egg sacs, immobilising prey, facilitating sperm transfer during mating, and even attracting mates. Some spiders add pheromones to lines of silk to indicate their sex and whether they have already mated or not. One type of spider silk has been shown to have the tensile strength of high grade alloy steel.

Giant spiders

One of the largest spiders in Ireland is the giant house spider. These impressive animals are often the subject of discussion, as their leg span can be up to 7.5cm and they can also move quickly, at speeds of up to half a metre per second. The giant house spider is the common name used for three distinct species of spider which look identical unless identified under the microscope, so the group is referred to as the Eratigena atrica complex. Perhaps most spider-wary people won’t spend too long pondering which species they are looking at when this impressive creature scurries by, but it is worth considering that females can live for several years. In return for keeping down the number of flies in your home, they have earned our compassion. The bite of these species does not pose a significant threat to humans or pets, and they are reluctant to bite, preferring instead to hide or escape.

Cool creatures

The spider world is remarkably diverse and full of species with unique features and traits. Many people’s favourite species is the zebra jumping spider. Often found in sunny locations such as on houses, sheds, and fences, this small black and white striped spider doesn’t build webs. Instead, they rely on their remarkably developed eyesight and speed to spot, stalk, and pounce on insect
prey. One of my personal favourites, and common in West Cork, is the interestingly named Sputnik spider. They are tiny, at just 1.5mm, and unremarkable in appearance, but it is their egg sacs that are extraordinary. Named after the world’s first artificial satellite, the shape of the sacs is similar to the satellite. If you look closely, their distinctive white egg sacs can be found attached to the underside of deciduous tree leaves.

The nursery web spider has maternal instincts to rival humans. She diligently uses her fangs to carry developing eggs in an egg sac while she moves about. When the eggs are ready to hatch, she spins a nursery tent out of silk for them. After putting them in the ‘nursery’, she will stand guard at the entrance, fiercely protecting her spiderlings as they develop. Another spider spectacle is the flower crab spider. These clever creatures lie in wait on flowers for visiting flying insects and then pounce on them. They are even able to change their colours to camouflage themselves on the flowers where they are lurking, helping them to hide from their prey.

Look closely to spot the uniquely shaped egg sacs of the Sputnik spider. (Photo :Ann Haigh)

Additional arachnids

All spiders are arachnids, but not all arachnids are spiders. Pseudoscorpions and harvestmen are also members of the arachnid group and are present in West Cork. Pseudoscorpions sound alarming, but they are harmless and tiny, usually only 2 to 5mm long. They have large pincer-like claws, resembling those of a scorpion, but unlike scorpions, they have no tail or stinger. They help control populations of small invertebrates by preying on mites, booklice, and other minute invertebrates. As for harvestmen, they are often referred to as ‘daddy long-legs’. This can be confusing, though, and is often used as an example by scientists to urge people to use Latin names instead of common names. Daddy long-legs can also be used as a term for the cellar spider and craneflies. Harvestmen may look like spiders, but they differ in that they do not produce silk, and only have two central eyes, while spiders have six or eight.

It is estimated that, even though all spiders use venom to immobilise their prey, only 1% of species in Ireland can bite through human skin. Clearly, compared to stinging insects, and even dogs, fears are not supported by evidence. However, while arachnophobes have my empathy, it is unfortunate that fear has replaced fascination for many, and spiders remain very misunderstood.