Most millipedes live somewhere between two and seven years, though the range across the class Diplopoda is enormous. Tiny flat-backed species in temperate forests may complete their entire life cycle in about a year and a half, while large tropical species and certain cave-dwelling millipedes can survive for a decade or more. That spread reflects the sheer diversity of the group, which includes over 12,000 described species occupying habitats from desert scrub to deep limestone caves. Understanding why lifespans differ so much requires a look at how millipedes grow, what threatens them, and how their environment shapes every stage of development.
Why Lifespans Vary So Much Between Species
Body size is the single most reliable predictor of how long a millipede will live. Small species in the order Polydesmida, the flat-backed millipedes common under logs in North American and European forests, tend to reach adulthood quickly and die within one to three years. One well-studied example, Polydesmus angustus, completed its full life cycle in roughly 16 months under controlled laboratory conditions with consistent warmth and humidity.1Global Change Biology. Combined effects of elevated temperatures and reduced leaf litter quality on the life‐history parameters of a saprophagous macroarthropod At the other end of the scale, giant millipedes in the order Spirostreptida regularly live five to seven years in the wild and have been documented surviving beyond ten years in captivity. The giant African millipede, Archispirostreptus gigas, is probably the best-known long-lived species, frequently kept as a pet and capable of reaching lengths over 30 centimeters.
The reason larger species live longer is partly mechanical. Millipedes grow by adding body segments and legs through repeated molts, and bigger species need more molts and more time to reach their full adult size. A species destined to carry 200 or more leg pairs simply cannot rush through development the way a species with 30 pairs can. Environmental harshness also plays a role. Desert-adapted spirostreptid millipedes like Orthoporus ornatus in the American Southwest and Archispirostreptus tumuliporus judaicus along the eastern Mediterranean coast show slower development rates than relatives in wetter habitats, suggesting that life-history pace tracks the availability of food and moisture.2Zoological Journal of the Linnean Society. Regional environments, life-history patterns, and habitat use of spirostreptid millipedes in arid regions
From Egg to Leggy Adult
A millipede’s life begins as an egg, usually laid in a small clutch in moist soil or leaf litter. Females of many species coat the eggs in a mixture of soil and fecal matter, forming a protective nest. Depending on the species and temperature, eggs hatch in a few weeks to a few months. The hatchling that emerges looks nothing like the adult. It typically has just three pairs of legs and only a handful of body segments, a far cry from the hundreds of legs the adult will eventually carry.
What follows is a mode of growth unique to millipedes and a few other arthropod lineages: anamorphosis, the addition of new body segments at each molt.3Frontiers in Zoology. Appearance of a transparent protrusion containing two pairs of legs on the apodous ring preceding the anamorphic molt in a millipede, Niponia nodulosa Every time a juvenile millipede sheds its exoskeleton, it emerges with more segments and more leg pairs than it had before. This is different from how insects develop; a beetle larva does not add body segments as it grows, but a millipede does, sometimes through a dozen or more molts before reaching adulthood.
Not all species handle this the same way. In some groups, segment addition stops at a specific life stage, and the animal never molts again after that final form is reached. In others, segment addition halts at maturity, but the animal keeps molting periodically throughout adulthood without gaining new segments. And in a third pattern, segments keep getting added at every molt even after the millipede is sexually mature.4ScienceDirect. Anamorphosis in millipedes (Diplopoda)— the present state of knowledge with some developmental and phylogenetic considerations These differences matter for lifespan because species that continue molting into adulthood tend to live longer. Each post-maturity molt represents additional metabolic investment, additional vulnerability, and additional time alive.
What Happens During a Molt
Molting is the most dangerous period in a millipede’s life. The animal must shed its entire exoskeleton, including the hard calcified plates that protect it from predators and desiccation. During and immediately after a molt, the new exoskeleton is soft and pale, leaving the millipede defenseless and prone to water loss. A millipede that molts in a dry or exposed location may not survive.
To manage this risk, many species build dedicated molting chambers underground. Some construct simple hollows in soil, but others go to impressive lengths. A species in the order Callipodida was observed building solid moulting chambers from substrate material reinforced with silk, taking about five days to complete the structure. The actual shedding process inside the chamber lasted roughly a month, about 29 days for females and 35 days for males.5PubMed. Mud and silk in the dark: A new type of millipede moulting chamber and first observations on the maturation moult in the order Callipodida During that time, the millipede is essentially immobile and completely reliant on the chamber’s protection. In long-lived species that molt multiple times as adults, this weeks-long vulnerability window recurs again and again over the animal’s life.
After the exoskeleton hardens and darkens over the following days, the millipede resumes feeding. Some species eat their shed exoskeleton to reclaim calcium and other minerals, which makes sense given how much energy goes into building each new suit of armor. The frequency of molting decreases with age. Juveniles may molt every few weeks during warm, moist conditions, while adults of longer-lived species might molt only once or twice a year.
How Environment Shapes How Long They Last
Millipedes are moisture-dependent animals. They lack the waxy cuticle that keeps many insects from drying out, so they lose water through their exoskeleton much faster than a beetle or ant would. This means humidity is the single most important environmental factor governing millipede survival. In dry conditions, millipedes retreat deep into soil or under rocks and become inactive, sometimes for months at a time.
Temperature and food quality interact with moisture in ways that can shorten or extend the life cycle. When Polydesmus angustus was reared at elevated temperatures with high-quality leaf litter, its population growth rate improved, meaning individuals developed faster and reproduced more efficiently. But when the same species was given lower-quality food with a higher ratio of carbon to nitrogen, development slowed and reproduction suffered, even if temperature stayed warm.1Global Change Biology. Combined effects of elevated temperatures and reduced leaf litter quality on the life‐history parameters of a saprophagous macroarthropod For wild millipedes, this means that climate change could simultaneously speed up development through warming and slow it down through changes in leaf litter chemistry, with the net effect hard to predict.
Seasonal patterns also shape lifespan. Desert millipedes in the American Southwest hibernate during the long dry season and emerge to forage only after warm-season rains. Their Mediterranean relatives, interestingly, do the opposite: A. t. judaicus in Israel forages during the warm dry months and hibernates through the cool, wet winter.2Zoological Journal of the Linnean Society. Regional environments, life-history patterns, and habitat use of spirostreptid millipedes in arid regions These extended dormancy periods effectively stretch the calendar lifespan. A millipede that spends half the year inactive may live the same number of active months as a tropical relative but survive twice as many calendar years doing it.
Chemical Defenses and the Cost of Staying Alive
Unlike centipedes, which are fast-moving predators armed with venomous forcipules, millipedes are slow herbivores and detritivores. Their primary survival strategy is chemical defense. Most millipedes have rows of glands along their body segments called ozadenes, which open to the outside through tiny pores called ozopores. When a millipede is grabbed or squeezed, these glands release noxious secretions that can repel ants, beetles, spiders, and other predators.
The chemistry varies by species. Some produce hydrogen cyanide, others quinones, and some synthesize terpenoid alkaloids that act as potent insect repellents even at very low concentrations. Experiments have shown that these alkaloids reduce attack rates by ants when applied to prey items, and field observations confirm that millipedes secrete visible droplets of these compounds when disturbed.6PubMed Central. The Chemistry of the Defensive Secretions of Three Species of Millipedes in the Genus Brachycybe Species that curl into a tight ball, like pill millipedes, combine physical armor with chemical deterrence, making them especially difficult for small predators to eat.
These defenses matter for lifespan because predation is one of the main sources of mortality in wild millipedes. Animals with effective chemical defenses survive more encounters with predators, which translates directly into longer average lifespans for the population. The flip side is that producing defensive chemicals costs metabolic energy, and individuals in poor nutritional condition may produce weaker secretions. A millipede living in nutrient-poor leaf litter has to allocate resources between growth, reproduction, and defense, with potential consequences for how long it ultimately survives.
Parasites and Disease
Millipedes host a range of internal parasites, particularly nematodes that live in the gut. Two major groups, the Rhigonematoidea and Thelastomatoidea, are found in millipedes worldwide and appear to infect virtually every individual in some host populations. Despite their prevalence, these nematodes are generally harmless. Researchers studying Japanese xystodesmid millipedes found that infection was universal but caused no observable damage, suggesting the relationship is closer to commensalism than true parasitism.7PubMed Central. Symbiosis of the millipede parasitic nematodes Rhigonematoidea and Thelastomatoidea with evolutionary different origins
That said, parasites are not always benign. A pathology study of giant African millipedes kept in a zoo found that nematodes, trematode eggs, and arthropod parasites were each present in a small percentage of specimens, and in some individuals these parasites were associated with gut damage and inflammation.8Veterinary Pathology. Histologic lesions of giant African millipedes (Archispirostreptus gigas) from a zoological institution Other individuals harbored adult nematodes without any visible tissue damage, reinforcing the idea that the relationship between millipedes and their gut inhabitants is complicated. In captive settings where millipedes cannot move to new foraging sites and may re-ingest parasite eggs from contaminated substrate, infections can build up in ways that would not happen in the wild.
Fungal infections are another concern, particularly in captivity. Millipedes that are kept too wet or in poorly ventilated enclosures can develop mold on their exoskeletons or internally. In the wild, bacterial and fungal pathogens likely contribute to mortality as well, though this has been studied far less than parasitic nematodes.
Keeping Millipedes in Captivity
Giant millipede species, especially Archispirostreptus gigas and various Spirobolus species, are popular in the exotic pet trade. Under good conditions, these animals routinely live seven to ten years, and some keepers report individuals surviving beyond that. The keys to longevity in captivity are substrate depth, humidity, and calcium availability.
A deep substrate of mixed hardwood leaf litter, rotting wood, and soil gives captive millipedes both food and burrowing space. The substrate should stay consistently moist but never waterlogged. Cuttlebone or crushed eggshell mixed into the substrate provides the calcium millipedes need to build each new exoskeleton after a molt. Without adequate calcium, molting problems are the most common cause of premature death in captive millipedes. The animal may become stuck in its old exoskeleton, or the new one may fail to harden properly, leaving it vulnerable to injury and infection.
Temperature matters too. Most tropical species do best between 21 and 26 degrees Celsius. Sustained cold can slow metabolism to the point where the animal stops feeding, and overheating above 30 degrees Celsius can be lethal, especially in combination with low humidity. Captive millipedes also benefit from a varied diet of decaying leaves from non-toxic hardwood trees, supplemented with fruits and vegetables. Avoid anything treated with pesticides, which can accumulate in the millipede’s body over time.
One advantage captive millipedes have over wild ones is the absence of predators and the buffered environment that eliminates drought stress. The main disadvantage is that captive conditions can promote the parasite buildup mentioned earlier, and that keepers sometimes mistake a molting millipede for a dead one. A millipede in its molting chamber can remain motionless for weeks. Disturbing it during this period can be fatal.
Cave Millipedes and the Slow Lane
Some of the longest-lived millipedes may be those that never see daylight. Cave-adapted millipedes, found in limestone systems across the world, show a suite of traits collectively associated with extended lifespans: reduced metabolic rates, slower growth, and lower reproductive output. These adaptations reflect the extreme resource limitation of cave environments, where all food ultimately enters as organic matter washed or carried in from the surface.9Ecological Research. Adaptation to a limiting environment: the phosphorus content of terrestrial cave arthropods
In a world with almost no food, growing slowly and living a long time is a better strategy than maturing fast and dying young. Cave millipedes tend to be smaller than their surface relatives and may take years longer to reach maturity. Their populations are tiny and fragile, and individual survival becomes correspondingly more important to maintaining the species. While precise lifespan data for cave millipedes is scarce because long-term studies in caves are logistically difficult, the metabolic and life-history evidence points to lifespans that could extend well beyond what surface species achieve.
Cave millipedes have also been valuable to researchers studying phosphorus limitation in terrestrial invertebrates. Because caves have so little available phosphorus, animals living there must allocate what they have carefully. Millipede exoskeletons are calcium-rich rather than phosphorus-rich, which may give them an advantage over soft-bodied cave invertebrates that need more phosphorus for growth. This quirk of their body chemistry may partly explain why millipedes are among the more successful colonizers of deep cave habitats.
How Researchers Estimate Millipede Age
Figuring out how old a wild millipede is presents challenges that do not exist with vertebrates. You cannot count rings, examine tooth wear, or measure telomere length in any practical way. Instead, researchers rely on two main approaches: counting body segments and tracking individuals over time.
Segment counting works because of anamorphosis. Since millipedes add segments at each molt, and the number of segments gained per molt is roughly consistent within a species, a millipede with more segments is older. By collecting large numbers of individuals and plotting their segment counts, researchers can identify distinct size classes that correspond to developmental stages, or stadia. The gap between stadia gives an estimate of how often molting occurs, and the number of stadia from hatching to adulthood gives a minimum development time. This approach breaks down for species that continue molting without adding segments after maturity, because post-adult molts leave no segment-count signature.
Mark-recapture studies, where individual millipedes are marked with paint dots or tiny tags and then recaptured over months or years, provide more direct lifespan data. These studies are labor-intensive and prone to low recapture rates, since millipedes spend much of their time underground where they cannot be found. Most published lifespan estimates for wild millipedes come from combining segment-count data with seasonal activity observations. You know when the young-of-the-year appear, you know how many stadia separate them from adulthood, and you know roughly how long each stadium lasts. Stack those numbers and you get a lifespan estimate, but it is always approximate.
Millipedes as Soil Ecosystem Engineers
A millipede’s lifespan matters beyond the individual animal because of the ecological role these creatures play. Millipedes are among the most important detritivores in forest soils worldwide. They consume fallen leaves, rotting wood, and other dead plant material, breaking it into smaller fragments and passing it through their gut. What emerges at the other end is fecal material enriched with microbial communities that accelerate further decomposition. In some temperate and tropical forests, millipedes process a measurable fraction of the annual leaf fall.
Longer-lived species contribute more to this process over their lifetimes simply because they eat more total material. But the relationship is not just about volume. Larger, longer-lived species tend to burrow more deeply, mixing organic matter into lower soil layers in a way that smaller species do not. Their molting chambers, abandoned after each molt, create small voids in the soil that improve aeration and water infiltration. And their calcium-rich exoskeletons, shed repeatedly over a lifespan of several years, return substantial amounts of calcium to the soil when they decompose.
In tropical forests where millipede diversity and abundance are highest, the aggregate effect of all this activity can influence nutrient cycling at scales that affect plant growth. Lose the millipedes from a forest floor and you slow decomposition, reduce calcium turnover, and compact the upper soil. The fact that individual millipedes in these systems can live five to ten years means that a single animal contributes to soil health across many seasonal cycles, not just one.