A spider that hasn’t moved for hours is almost always doing something. For most spiders, stillness is the strategy: they live on a slow, low-energy budget built around waiting rather than chasing. Staying put also keeps them out of sight of the animals that eat spiders, so the same habit feeds them and protects them. Some spiders sit still for other reasons, such as resting in a safe spot, guarding eggs, or getting ready to shed their skin.
Most Spiders Hunt by Waiting
A web spider waiting at the center of its web is tuned in to vibrations running along the threads. While it waits, some orb-web spiders pull the spokes of the web inward toward the center, tightening them.1PubMed Central. Attention focusing in a sit-and-wait forager: a spider controls its prey-detection ability in different web sectors by adjusting thread tension Tighter threads carry vibrations better, so the spider responds faster to an insect that hits the web.2PubMed Central. Attention focusing in a sit-and-wait forager: a spider controls its prey-detection ability in different web sectors by adjusting thread tension It pulls harder on the spokes running up and down than on those running side to side, and it notices prey in the upper and lower parts of the web more often.3PubMed Central. Attention focusing in a sit-and-wait forager: a spider controls its prey-detection ability in different web sectors by adjusting thread tension
Its legs often rest on the main threads, like fingers on strings. It may stay there for hours, day or night, depending on when its prey flies. When something lands, it moves suddenly and fast, then returns to the same spot. That’s why poking the web often makes it rush out. After wrapping or biting the catch, many orb-web spiders carry it back to the hub or eat it where it was caught, then settle back into the same posture.
Spiders that don’t build catching webs are often ambush hunters, staying motionless in one place until an insect wanders close. Some crab spiders flatten their bodies to squeeze into tiny gaps and wait for prey there.4A-Z Animals. Crab Spider Waiting works because insects come and go constantly, so a well-placed spot brings food in without any searching.
Indoors, many spiders build loose webs in corners and wait there for weeks. Corners near lights or windows attract flying insects, so a spider that stays in one corner has usually found a spot that keeps catching food.
The spider you see by day may also not be the one hunting at night. Many orb-weavers build a fresh web in the evening and take it down or leave it in the morning, so a spider sitting in the open by day may be resting rather than hunting. Some retreat to a leaf or crack beside the web and keep a thread attached to it, so the same spot gets used again and again.
Staying Still Saves Energy
Closely related spiders that hunt on foot burn more energy at rest than those that build webs.5ScienceDirect / Elsevier (J Insect Physiol.). Leaving the web: Testing the link between predation style and resting metabolic rate using closely related spiders with contrasting lifestyles So a spider’s way of hunting shapes how fast its body uses energy.6ScienceDirect / Elsevier (J Insect Physiol.). Leaving the web: Testing the link between predation style and resting metabolic rate using closely related spiders with contrasting lifestyles
Building a web takes a real share of a spider’s energy. In one funnel-web spider, fewer than 1 in 100 spiders moved their web on any given day.7PubMed. Energetic cost of web construction and its effect on web relocation in the web-building spider Agelena limbata The energy cost of building a new web is a main reason they stay where they are.8PubMed. Energetic cost of web construction and its effect on web relocation in the web-building spider Agelena limbata
Even moving their legs works differently. Spiders don’t have muscles to straighten some of their leg joints; they extend their legs by pushing fluid into them under pressure.9Journal of Experimental Biology. The Hydraulic Mechanism of the Spider Leg That pressure can briefly jump to several times its resting level during a quick movement.10Journal of Experimental Biology. The Hydraulic Mechanism of the Spider Leg Bursts of action are possible, but spiders tend to save them for when they count.
That thrift shows in how long they can go without food. Many spiders survive weeks or even months without eating, and a slow metabolism lets them wait out dry spells with few insects.
It’s easy to assume a spider that hasn’t moved in days is dead, but it is usually alive. Dead spiders often curl their legs tightly under the body, while a living spider at rest usually has its legs extended or gripping silk.
A warm-blooded animal burns a lot of fuel just keeping its body temperature up, while a spider does not, which is a big reason it can get by on so little food. A spider’s body temperature follows its surroundings, so in a cool room it slows down further and uses even less energy. That’s why a spider in a cool basement or garage may look almost motionless, while the same spider in a warm sunny window is more active.
Hiding From Predators
Many spiders build or use a retreat, such as a silk tube, rolled leaf, or crevice. Where lizards hunted near the ground, they cut the number of exposed spiders by about two-thirds but didn’t affect spiders in silk shelters.11PubMed Central. Self-made shelters protect spiders from predation
A retreat gives a spider a place to duck into where larger animals cannot easily see or reach it. Many web spiders keep one foot on a signal thread running from the retreat to the web, so they can feel prey from a hidden spot and rush out only when it is worth it. A spider that seems to be missing from its web may be sitting just out of view, not gone.
Birds, lizards, wasps, and other spiders all hunt spiders, and many of these predators find prey by spotting movement. So the less a spider moves, the less likely it is to be noticed. Many animals, including invertebrates, can freeze completely when threatened, and predators tend to lose interest in prey that has gone motionless.12PubMed. Tonic immobility as a survival, adaptive response and as a recovery mechanism
For a small spider, freezing beats running. Running makes it far more visible to a predator tuned to detect movement, while a motionless spider can blend in with bark, leaves, or shadow. Many spiders are colored and shaped to match the surfaces where they rest, which makes stillness more effective.
If you disturb a still spider, it may freeze harder, curl up, or drop on a silk line. Some run into their retreat and stay hidden for a long time afterward.
Other Reasons a Spider Won’t Budge
Spiders grow by molting, shedding their hard outer skin and replacing it with a larger one. Before a molt, spiders hide in a burrow or retreat and stop eating.13Cornell University Library. Growing Spiders Most common spiders hang from a silk thread to molt, while tarantulas lie on their backs on a silk mat.14Cornell University Library. Growing Spiders A spider that seems sluggish and ignores food may be preparing to molt, and a tarantula on its back is usually molting, not dead.
Signs of an approaching molt include hiding more and refusing food for days, and the body may look duller or darker. Afterward you may find an empty spider-shaped skin nearby, often mistaken for a dead spider. A freshly molted spider is soft and stays still while its new skin hardens.
A spider hanging motionless from a thread with its legs loosely curled may be in the middle of a molt, which can take a while and leaves it very vulnerable. Watching quietly for a day usually settles it: a molting spider is eventually replaced by a shed skin and a larger, softer spider, while a dead one just stays put.
Some mother spiders stay with their egg sacs until the young hatch. Green lynx spider mothers that guard their eggs lay fewer eggs over their lives, but more of their young survive.15Elsevier / Animal Behaviour. Costs and benefits of maternal behaviour in the green lynx spider (Oxyopidae, Peucetia viridans)
To spot a guarding spider, look for a round silk ball held in the jaws, attached to the web, or nearby. The mother may keep her body over the sac or hold it close, and will often skip meals while she stays with it. She may defend it, rearing up or lunging at an intruder, even though she is usually harmless to people. Not all spiders guard their eggs, though. Many lay a sac, leave it, and never return, so a still spider is not always a mother. Leaving a guarding spider alone lets the young hatch and disperse.
Spiders can’t control their body heat, so where they sit affects how warm or cool they are. Young flat rock spiders pick warmer resting spots, and that choice helps them grow and survive.16Ecology. Fitness benefits of retreat‐site selection: spiders, rocks, and thermal cues In hot weather, some spiders shelter under large rocks that stay cooler during the day.17Ecosphere. When hot rocks get hotter: behavior and acclimatization mitigate exposure to extreme temperatures in a spider
Should You Move a Spider That Won’t Leave
Most house spiders are harmless to people and eat insects, so a spider that stays in one corner is helping control pests. Because spiders rarely move webs on their own, it will likely stay until disturbed or until food runs out.18PubMed. Energetic cost of web construction and its effect on web relocation in the web-building spider Agelena limbata
A spider in a high corner is out of the way of daily life and catches small insects such as flies and gnats that you would rather not have around. Most house spiders have no interest in people and will not bite unless they are squeezed or pinned against skin. If a web bothers you, you can remove it with a broom or vacuum, though the spider may simply rebuild nearby.
Real trouble looks different from stillness. Signs include not reacting at all to a gentle puff of air for a long time, falling repeatedly, or being unable to grip surfaces.
If you do want to move one, choose a clear cup or jar wider than the spider and place it gently over the spider so its legs are not caught under the rim. Slide a stiff piece of paper or card under the cup, keeping the spider inside, then lift the cup and card together. If the spider is on a wall, gently coax it into the cup rather than trapping it against the surface, which reduces the chance of injuring a leg.
Carry it outside and release it near a shrub, woodpile, or other cover, tipping the cup sideways and letting the spider walk out on its own. A sheltered spot matters, since exposed spiders are easier prey.19PubMed Central. Self-made shelters protect spiders from predation Avoid moving a spider that is molting or guarding eggs, because it’s vulnerable then.
To make a spot less attractive, reduce insects near lights or windows so there are fewer meals there. Clearing clutter removes hiding places, and sealing gaps keeps outdoor spiders from coming in.
If you can’t identify the spider, know that in most homes in many regions a spider sitting still in a corner is a harmless house spider, but a few places have species with medically significant bites. If you live somewhere with black widows or recluse spiders, avoid handling the spider with bare hands and use a cup and card from a distance. If a spider has bitten someone and they have severe pain, spreading redness, or feel unwell, seek medical care and, if safe, save the spider for identification.