Spiders eat other spiders, and it happens more often than many people expect.
Spider cannibalism and spider-on-spider hunting can occur when food, mates, or territory are at stake.
You may see this in direct attacks, mating fights, or when a bigger spider catches a smaller one in a web or shelter.
In some cases, spiders target their own young or siblings, and some species make a habit of it.
The Short Answer And When It Happens
Spiders eat other spiders for different reasons.
In spider behavior, the line between hunting and cannibalism can be very thin, especially when another spider is close by.
Predation Vs. Cannibalism
One animal hunts and eats another during predation.
Cannibalism happens when the prey is the same species, and it can include sexual cannibalism, sibling cannibalism, or even matriphagy, where offspring eat the mother.
Why Spiders Turn On Other Spiders
Spiders attack other spiders when food is scarce, when a mate is nearby, or when they guard web space.
Larger spider predators may target smaller spiders, so attacking first can be a survival move.
How Common The Behavior Really Is
Many spiders eat other spiders to gain a high-protein meal and reduce competition.
This behavior appears in many species, though not every spider does it often.
Common Situations Where One Spider Eats Another
You are most likely to see spider-on-spider eating during mating, when web space is contested, or when young spiders compete for survival.
These moments create strong pressure, and a spider may see another spider as food or as a threat.
Mating Encounters Gone Deadly
A female may eat a male before, during, or after mating.
Spiders such as the black widow spider and the redback spider, Latrodectus hasselti often show this behavior, where the male may be injured or consumed after approaching a female.
Competition Over Food And Web Space
When two spiders want the same hunting spot, one may kill and eat the other.
This is common in crowded areas where food is limited, and species like Stegodyphus lineatus show aggressive interactions that can end in cannibalism.
Spiderlings And Juvenile Survival
Sibling cannibalism can happen among spiderlings if food is scarce or the brood is crowded.
In some species, the strongest juveniles survive by eating smaller siblings before they can compete for the same resources.
Spider Species Known For Eating Spiders
Some spiders make other spiders a regular part of their diet.
A few are famous for it, while others do it only when the chance is right.
Cellar Spiders In Homes
The common cellar spider, Pholcus phalangioides, often eats other spiders indoors.
In homes, the cellar spider may catch larger spiders in corners, basements, and garages, making it a useful hunter in quiet spaces.
Pirate Spiders As Specialist Hunters
Pirate spiders hunt other spiders and invade their webs.
A pirate spider uses patience and stealth to catch web builders that are much larger than itself.
Unusual Cases In Wolf And Jumping Spiders
Some wolf spiders, like Allocosa brasiliensis, and jumping spiders, like Evarcha culicivora, also eat other spiders.
These cases are less common than in web hunters, but they show that spider cannibalism and araneophagy can appear in very different spider groups.
What This Behavior Means In Nature And Around The House
Spider-eating-spider behavior can help control populations and remove weaker rivals.
It gives the winner a high-protein meal, which supports growth, egg production, and survival in a tough habitat.
Population Control And Survival Benefits
This behavior can lower competition and keep the strongest spiders in a space.
That can help a species stay balanced when prey is limited and may support faster growth for the spider that wins the fight.
What Homeowners And Gardeners Should Take From It
When you see one spider eating another near your home, it usually signals local competition, not a threat to you.
You can leave harmless spiders alone if they help with pest control. If they are in a spot you do not want them, gently remove them.
