How Long Can a Spider Go Without Eating?

Most spiders can survive weeks to months without a single meal, and some species push well past that. In laboratory studies, false widow spiders have survived more than eight months of total food deprivation, and researchers who work with wandering spiders describe fasting periods of four to eight weeks as perfectly normal for those animals. The range is wide because “spider” covers over 50,000 known species living in deserts, caves, rainforests, and your basement, and each has evolved its own capacity for riding out lean times.

General Timeframes by Spider Type

There is no single number that applies to all spiders, but some rough patterns hold. Small, active hunting spiders like jumping spiders tend to have shorter fasting limits, often a few weeks to a couple of months, because they burn energy chasing prey and have less body mass to draw on. Larger web-building species do better. Orb weavers and cobweb spiders can commonly go one to three months, partly because sitting in a web costs far less energy than sprinting after a fly. Among the champions are species adapted to environments where food is unpredictable. Cave spiders routinely overwinter without eating for several months, relying on internal reserves built up during warmer seasons.

One of the more striking examples comes from research on the false widow spider, Steidodyphus grossa. In a controlled experiment, starving females reached a point where more than half had died by about week 34 of food deprivation, while well-fed females were still 58% alive at week 42 when the study ended.¹ That means a substantial fraction of these spiders endured roughly eight months without food before dying, and some were likely still clinging on even past that point. For a wandering spider (Cupiennius salei), researchers described hunger periods of four and eight weeks as “a natural situation,” with the spiders losing body weight but otherwise carrying on.²

How Spiders Slow Down to Stay Alive

The secret to surviving months without food is not just having reserves but spending them slowly. Spiders are ectotherms, meaning their body temperature tracks the environment around them. When it is cool or when food disappears, their metabolic rate drops on its own. But beyond that passive slowdown, spiders actively reduce energy consumption during fasting.³ Oxygen consumption and carbon dioxide output fall gradually as starvation progresses, a measurable sign that the body is throttling down its activity.⁴

The primary fuel during this slowdown is fat. Spiders store lipids in specialized cells scattered through their bodies, and these reserves are the first thing consumed when food stops arriving. A spider that entered starvation with generous fat stores can coast on them for quite a while. A study on spiderlings overwintering found that their lipid content dropped by about 28% over the cold months, even though overall survival declined by only around 20%.⁵ The fat was being steadily burned to keep the animal alive through a period with essentially no food.

What Happens When Fat Runs Low

Fat is the first line of defense, but it does not last forever. As lipid reserves shrink, spiders start tapping into other survival mechanisms. One of the more remarkable is autophagy, a process where cells digest their own non-essential components to recycle the raw materials. Researchers studying the European cave spider (Meta menardi) during controlled winter starvation found that by the middle and end of the overwintering period, the cells lining the spider’s midgut were packed with the cellular structures associated with autophagy. The breakdown products released from this self-digestion serve as building blocks for critical macromolecules, essentially letting the spider cannibalize parts of its own cells to keep the rest functioning.

Genomic work on the huntsman spider (Heteropoda venatoria) fills in more of the picture. In the late stages of starvation, genes involved in fatty acid metabolism and protein degradation ramp up dramatically, and autophagy pathways become significantly more active.⁶ This is the spider’s body shifting from burning stored fat to breaking down proteins and recycling cellular machinery. It is a last-resort strategy and not one that can sustain the animal indefinitely, but it extends the window of survival well past what fat alone would permit.

Why What a Spider Ate Before Matters

Not all meals are created equal when it comes to surviving a fast. Wolf spiders fed lipid-rich prey before being starved lived longer than those that had been eating protein-rich prey.⁴ The reason is straightforward: fat-rich food translates directly into larger lipid reserves, and since fat is the main fuel burned during starvation, spiders with bigger fat deposits simply have more to burn before they hit the danger zone.

This finding has practical implications for anyone keeping spiders in captivity. Feeding a pet spider a varied diet that includes naturally fatty prey items can meaningfully improve its resilience if you ever go away for a long weekend or forget a feeding cycle. It also explains why spiders in the wild seem to prefer certain prey when available. A spider does not “know” which insects are lipid-rich in any conscious sense, but natural selection has shaped foraging preferences that tend to build the kind of reserves that matter most when the next meal is uncertain.

How Starvation Changes a Spider’s Behavior

Hunger does not just burn through internal reserves. It changes how spiders act. One of the more fascinating demonstrations comes from that same false widow spider study. Starving females completely lost their ability to reproduce, yet they kept producing silk and building webs. More than that, they shifted the architecture of their webs, spinning proportionally more prey-capture silk and less of the structural “safety silk” that protects the spider itself.¹ In other words, as starvation deepened, these spiders took on more personal risk in exchange for a better chance of catching something to eat. It is a calculated trade-off driven by desperate circumstances.

Even more surprisingly, the starving females maintained their sexual signaling. Males were equally attracted to the webs of starving and well-fed females, and they courted for the same amount of time on either type of web.³ Since the starving females were completely infecund, the researchers described this as a form of deceptive signaling. The females could not reproduce but kept advertising anyway, perhaps because attracting a male also means attracting a potential meal. Despite the common assumption that starving widow spiders would become more cannibalistic, sexual cannibalism did not increase with starvation in this experiment. Only a single male was killed by a starving female.

Wolf spiders show a different set of behavioral adjustments. After 14 or 28 days of food deprivation, these spiders attacked the first prey item offered within one to five minutes, with no hesitation regardless of how long they had been starving.⁷ Hunger did not make them faster to pounce on the first opportunity. What changed was the time between the first and second attack. Spiders that had been starved longer took significantly longer to go after a second prey item, possibly because they were processing the first meal more thoroughly. On average, the spiders attacked about four prey items per session, and they became more efficient at extracting nutrients from each one as they caught more, spending less handling time per item.

Venom and Silk Production During Fasting

You might expect a starving spider to run low on venom, since producing it takes energy and raw materials. But at least in Cupiennius salei, hunger periods of up to eight weeks had no effect on the amount of venom a spider could release. The spiders lost body weight during those fasting weeks, but their venom supply stayed constant.² From the spider’s perspective, this makes evolutionary sense. Venom is the tool that lets a spider subdue prey when prey finally appears. Running out of venom during a famine would be catastrophic, since the spider might encounter a meal but be unable to capture it. Maintaining venom production even at the cost of body mass is a worthwhile investment.

Silk tells a different story. Research on orb weavers and other web-building species suggests that starvation degrades silk quality. In one study, silk from starving spiders was visibly thinner, less abundant, and far more fragile than silk from well-fed spiders. It broke easily during collection and appeared less robust overall.⁸ Silk is protein-intensive, and a starving spider simply does not have the amino acid budget to produce the same quality material as a well-fed one. This creates a dilemma for web-building species. They need silk to catch food, but the less they eat, the worse their silk gets, making it harder to catch food. The false widow’s strategy of shifting silk investment toward prey capture rather than safety may be one way spiders cope with this downward spiral.

The Surprising Link Between Hunger and Longevity

One counterintuitive finding from spider research is that moderate dietary restriction can actually extend lifespan. Wolf spiders (Pardosa pseudoannulata) kept on continuously restricted diets lived longer than those fed without limits.⁹ The catch is that the restricted spiders grew more slowly and stayed smaller. There appeared to be a direct trade-off: energy that would have gone into growth was redirected toward maintenance and survival.

Even more interesting, spiders that were restricted as juveniles and then given unlimited food as adults did not keep the longevity benefit. Their weight returned toward normal, but their lifespan actually decreased compared to spiders that stayed on the restricted diet. This suggests the longevity effect is not just about being small. The ongoing state of mild caloric restriction seems to maintain some protective physiological state that is lost when abundant food returns. This mirrors findings in other animal groups where caloric restriction extends lifespan, though the specific mechanisms in spiders are still being worked out.

Why Your House Spider Is Probably Fine

If you have found a spider in a corner of your home and are wondering whether it is slowly starving, the answer is almost certainly no, at least not yet. Indoor environments tend to harbor more small insects than people realize, and a single web in a good location can catch enough gnats, flies, and other tiny arthropods to sustain a spider for weeks between visible catches. Cobweb spiders like the common house spider (Parasteatoda tepidariorum) are particularly well-suited to low-food environments because their metabolic needs are modest and their webs are low-maintenance structures that continue catching prey passively.

Even in genuinely food-poor situations, the research makes clear that spiders have deep reserves. A spider that has not caught anything in a month is not necessarily in crisis. It has likely slowed its metabolism, started drawing on fat stores, and adjusted its web or hunting strategy to improve its odds. The animal you see sitting motionless in the corner is not idle. It is conserving energy with a precision that took hundreds of millions of years of evolution to fine-tune.

When Starvation Gets Dangerous

Despite their impressive fasting abilities, spiders are not invincible. Extended starvation carries real costs beyond weight loss. In the false widow study, starving females had a 71% greater mortality risk than fed females over the same time period.¹ Reproduction shuts down entirely well before death. Those same starving females that survived for months and kept building webs and attracting males produced zero offspring. For a species whose evolutionary purpose is to reproduce, weeks of survival without the ability to pass on genes is, in a biological sense, already a form of failure.

The weight loss itself is not as dramatic as you might think. Wolf spiders deprived of food for 14 to 28 days lost an average of about 11% of their body weight, and there was no significant difference in weight loss between the two-week and four-week groups.⁷ This suggests that early starvation costs the body relatively little, with the metabolic slowdown kicking in quickly enough to limit mass loss. The real danger zone comes later, when fat stores are depleted and the spider shifts to cannibalizing its own cellular machinery through autophagy. At that point, organ function begins to degrade, silk quality drops, and the spider becomes increasingly fragile.

Temperature also plays a role in how long the reserves last. A spider in a cool basement burns through its fat far more slowly than one in a warm attic, simply because metabolic rate scales with temperature. This is one reason cave spiders are among the most extreme fasters. Their environment stays cool and stable year-round, minimizing caloric expenditure and letting stored lipids stretch across an entire winter.

Water Matters More Than Food

A question that often comes alongside “how long without food” is “how long without water,” and the answer is quite different. While spiders can go months without eating, most species become severely stressed within days to a couple of weeks without access to moisture. Spiders drink water droplets from webs, surfaces, or even condensation on cave walls, and dehydration kills them far faster than starvation does. This is why a spider in an arid corner of your attic may be in more trouble than one in a damp basement, even if neither has caught a fly recently.

For anyone keeping a pet tarantula or other captive spider, maintaining a small water dish or regularly misting the enclosure is considerably more important than adhering to a rigid feeding schedule. A healthy, well-hydrated spider with decent fat reserves can comfortably skip meals for weeks. A dehydrated spider with a full belly is in far more immediate danger.