The cellar spider (Pholcus phalangioides) is named aptly because it prefers dim and dark places such as your basement (or attic). People have constructed buildings worldwide with spaces that are the perfect habitat for cellar spiders.
It has two groups of three eyes (as if you are going to count them!) and two more in the middle – eight altogether. It also has two grayish body parts: The front contains the brain and venom glands, the back (the abdomen) contains the organs, including silk glands. All eight long and flexible legs are attached to the front. Females can be up to one-third of an inch in length, while their forelegs can be 2 inches long – five or six times as large as their bodies (males are slightly smaller) – earning the name daddy longlegs.
Do not confuse this spider with harvestmen, a related “opilionid” also sometimes called daddy longlegs. They are not spiders at all and live outdoors.
Although these spiders are native to warm parts of Europe and Asia, you might encounter them no matter where you go today, because people have carried them to every continent except Antarctica. These spiders hang upside down from irregular webs in damp and dark places, which can include caves and abandoned burrows as well as high corners of a cellar or attic.
Unlike other webs, these are not sticky; the spider relies instead on vibrations to trap prey. They remain motionless until unsuspecting prey touches the web strands, then rush out to wrap the prey in its silklike threads.
It uses its second and third pairs of legs to rotate the prey and its fourth pair of legs to wrap the prey in threads from its spinneret glands, with its long legs helping it stay out of biting range. After wrapping the prey, the spider bites it to inject venom – maybe eating immediately, maybe saving it for a later snack. When it has finished consuming the victim, it untangles the prey and lets the remains drop to the ground.
The silk has antimicrobial properties. Researchers hope that in the future, spider silk can be used against bacteria that are resistant to antibiotics.
Sometimes these spiders spin when prey gets entangled – it is not known why, but some scientists think the whirling makes it difficult for large prey to see and attack the spider, or that the spinning vibrations entangle prey and prevent it from escaping – and for this reason, this spider is sometimes called the vibrating spider.
A female cellar spider lays up to 60 eggs at a time. She wraps the eggs in silk threads and carries them around using her jaws. When the eggs hatch, the spiders crawl onto the mother’s body for a time. As they grow, they shed their exoskeleton many times, reaching adulthood at about one year and living for two to three years. The spiders often walk with an alternating gait: First, they move forward the front right leg, then the second left leg, then the third right leg and so on.
They are not social, and come together only to mate. Males try to mate with the largest females. Scientists think that’s because mating with the largest females increases reproductive success, as larger females lay more eggs. After mating, the female chases the male away. Sometimes the little male may be eaten instead.
Usually cellar spiders eat insects – and often also eat other spiders or their eggs. So if you dislike spiders, let this one be: It will do you a favor and help rid your basement of other spiders as well as flies, centipedes, ants and other creepy crawlies. These spiders don’t often leave their web, rarely travel far and never attack people.
In fact, they are extremely passive toward people.
There is a myth that daddy longlegs are one of the world’s most toxic spiders but because their fangs are short, they cannot bite people. This is, of course, not true. This myth perhaps arises because these spiders sometimes eat spiders that can kill people and therefore must have extremely toxic venom to kill such deadly prey? If you have watched “Mythbusters,” you might recall an episode in which the show’s host, Adam Savage, was bitten by a cellar spider. He felt the bite – a mild, short-lived burning sensation – and when the venom was analyzed, it was found to be not especially potent.
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Jeanine Farley is an educational writer who has lived in the Boston area for more than 30 years. She enjoys taking photos of our urban wild things.
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