Wasps are social insects that live in colonies and build nests out of paper made from chewed-up wood fibers mixed with saliva. A wasp colony typically lives for one year. In temperate climates, wasp nests are built in the spring and summer, reach peak size by late summer, and are abandoned in the fall when cold weather arrives. This leaves the question – what happens to those old, abandoned wasp nests?
Do wasps reuse old nests?
Wasps do not reuse old nests. Each spring, the wasp queen emerges from hibernation and begins building a brand new nest. She chooses a location, builds a small starting nest out of chewed wood pulp, and lays her first eggs. When the eggs hatch into larval wasps, the queen feeds them, and when they grow into adult worker wasps, these workers take over expanding the nest and caring for the next generation of larvae.
As the colony grows through the spring and summer months, more layers and combs are added onto the nest to accommodate all the wasp brood and stored food. But once cooler fall weather sets in, the wasp colony begins to decline. The queen stops laying eggs, the remaining larvae develop into males and new queens, and the colony ultimately abandons the nest and dies off when winter arrives, except for the fertilized new queens who leave to hibernate for the winter.
Why wasps don’t reuse nests
There are a few key reasons why wasps build new nests each year rather than reusing old ones:
- Nests naturally degrade – The paper nests are made of chewed wood fibers mixed with saliva. This material naturally breaks down over time when exposed to weather.
- Parasites and pathogens accumulate – Old nests harbor more parasites like mites and fungi that can harm developing wasps.
- Nest architecture is inflexible – Nests are built for one season’s needs. It’s easier to build a new nest layout than modify an old one.
- Lack of insulation – Old nests lose their insulation value after exposure to winter weather.
- Territoriality – Wasps aggressively defend nesting areas. Old nest smells may deter wasps from moving back in.
Starting with a new, clean nest each year gives the wasp colony the best chance at healthy growth and reproduction. The specific nest location may be reused from one year to the next, but never the same physical nest structure.
What happens to paper wasp nests after abandonment?
After paper wasp colonies abandon their nests in fall, the leftover nests remain attached to eaves, trees, or wherever they were built. The fate of these abandoned paper nests can be:
Gradual decay from weathering
The natural paper nest material breaks down slowly when exposed to the elements. Rain, snow, wind, and temperature extremes cause the nest to degrade over time. The paper envelope becomes brittle and fragments of the nest get dislodged. This gradual decay may take several seasons until the nest is entirely gone.
Knockdown by animals or humans
Larger animals like raccoons or bears may knock down all or parts of an abandoned wasp nest while climbing on trees or buildings. Rodents like mice or squirrels may nibble on the nest material for food or nest insulation. Humans will frequently knock down visible nests that are built in living areas, for safety and aesthetics. This mechanical removal speeds up the nest decay process.
Scavenging by insects and animals
The old wasp nests are sources of food and nest material for other creatures. Birds may pull fiber strands from the nest to reinforce their own nests. Mice, squirrels, and other rodents may take fibers for nest insulation. Wood-boring beetles feed directly on the nest paper fibers. Many species of flies, moths, bees, and spiders may take over the abandoned nest as a temporary shelter.
Burning
If the wasp nest is within reach, people may intentionally burn the nest to more quickly remove it. Large nests high up in trees or in building eaves are sometimes burned out using a flaming ball attached to an extension pole. The nest is reduced to ash and accelerated on its way to disappearing.
Can you safely remove an old wasp nest?
Old, abandoned wasp nests are safe to remove as long as there are no live wasps still living in the nest. Some tips for safe removal:
- Wait until cooler weather when wasp activity has declined or ceased
- Spray the nest with wasp killer insecticide 1-2 days before removing, to kill any remaining wasps
- Wear protective clothing like a bee suit, gloves, and goggles
- Work at night when all wasps are in the nest and less active
- Use an extension pole with a scraping tool to knock down nests out of reach
- Seal openings in walls or eaves after nest removal to discourage new nests
- Double bag the removed nest pieces in sealed plastic bags and dispose
With proper timing and safety precautions, old wasp nests can be removed and discarded without risk of insect stings. However, if live wasps are seen foraging around the nest, it’s best to delay removal until wasp activity has ceased for the season.
What is the lifecycle of a wasp nest?
The typical lifecycle of a wasp nest over one year goes through these stages:
Spring: Nest initiation
– Queen emerges and selects nesting site
– Makes starter nest the size of an apple
– Lays first eggs in paper comb cells
– Feeds larvae that hatch from eggs
Early Summer: Rapid growth
– Larvae develop into worker wasps
– Workers expand nest size dramatically
– Queen remains inside laying eggs
– Up to several thousand wasp cells added
Mid to Late Summer: Peak maturity
– Nest reaches maximum size
– Contains up to 15,000 wasp cells
– Hundreds to thousands of adult wasps tending the nest
– Foraging activity peaks
Fall: Decline and abandonment
– Queen stops laying eggs
– Last brood develops into males and new queens
– Males and queens mate, then leave the nest
– Colony begins to decline and gradually abandons the nest
– Nest left vacant as cold weather arrives
This cycle from initiation to abandonment completes in roughly 6 months. The nest grows rapidly during peak summer brood production, then is left behind once the colony dies off in fall.
Do wasp nests biodegrade or decompose?
Wasp nests are made of wood pulp, saliva, and excrement. This organic material will gradually biodegrade and decompose back into the environment. However, the high fiber content means nests break down relatively slowly compared to other insect nest materials.
Factors speeding decomposition include:
– Exposure to weathering – Alternating wet and dry, freezing and thawing
– Mechanical abrasion – From wind, falling branches, animals
– UV radiation from sunlight – Breaks down fibers
– Microorganisms – Bacteria, fungi, and protozoans digest cellulose
– Scavengers – Insects, mammals, and birds that eat the nest
– Fire – Rapidly oxidizes the nest carbon into ash
Under natural conditions outdoors, an abandoned wasp nest may take 1-2 years to fully decompose. Indoors, nests may persist many years before falling apart since they are protected from weather, sun exposure, and scavengers.
Can you compost old wasp nests?
Wasp nests made of paper are technically compostable materials, being organic and biodegradable. However, composting intact nests is not recommended for a few reasons:
- Slow decomposition – High fiber content breaks down slowly
- Risk of wasp recolonization – Compost warmth may attract new queens
- Sanitation – Old nests may contain parasites or pathogens
- Presence of other insects – Nests may harbor unwanted pests
- Physical contaminant – Nest fragments don’t break down readily
A better option is to manually break up the nest remains into small pieces using gloves and dust masks for safety. The small fibers can then be mixed into compost piles or directly worked into garden soil or mulch where they will slowly decompose over time.
Do any animals or insects reuse abandoned wasp nests?
While wasps themselves do not reuse nests, some other species may take over old wasp nests for their own purposes:
Swarms of honeybees
Honeybees, especially reproductive swarms in search of a new home, may take over the void left by an abandoned wasp nest. The ready-built nest with combs and cavities provides a head start versus building their own wax comb nest.
Solitary wasps and bees
Many non-social wasps and solitary bees will lay their eggs in the protected recesses of old nest papers. Cavity-nesting species like orchard mason bees may fill up vacant wasp nest cells.
Polistine paper wasps
A smaller related paper wasp species may rebuild and add new brood comb onto the structure of an old nest previously built by a larger wasp species.
Yellowjackets
Yellowjacket colonies are annual like paper wasps, but a spring queen may occasionally move into an old abandoned paper wasp nest if the site is highly favorable.
Hornets
Giant hornets chew wood pulp like wasps. A hornet queen may rarely nest in a previously used paper wasp nest.
Caterpillars and moths
Moth and butterfly caterpillars may scrape fibers from old nests to reinforce their cocoons for pupation or chew the paper to ingest trace nutrients.
Spiders and other insects
Many insects like ladybugs, earwigs, ants, termites, and spiders may nest in old wasp nests for protection through the winter. The crevices provide insulation and shelter.
Mice and other rodents
Mice or tree squirrels may extract fibers from unoccupied nests to line their own nests for warmth. The cavities may also provide refuge from predators and winter weather.
So while wasps themselves reuse nothing from past nests, the durable paper material of abandoned nests does provide resources that can be exploited by a variety of other species once the wasp colony is gone.
Conclusion
Wasps build intricate paper nests each year that are abandoned and left behind once cooler weather arrives. These empty gray structures clinging to eaves and tree branches meet varied fates throughout their slow decay process. Gradual weathering may take 1-2 years to fully decompose an abandoned nest. But the durable fibers also provide valuable resources that many insects, birds, and mammals can reuse in various ways. With a lifespan of just one active season, the humble wasp nest fulfills its purpose and is cast aside, soon to melt back into the earth to nourish new life.
