Wasps are social insects that live in colonies with one queen. The queen is the only female wasp capable of reproducing and laying eggs. She is the heart of the colony – without her, the colony cannot survive for long. So what happens when a wasp queen dies unexpectedly?
The colony collapses
When a wasp queen dies, the colony she founded collapses shortly after. Without a reproductive queen, no new worker wasps can be produced to replace old workers as they die off. The existing workers only live for a few weeks in the summer. So within a couple of months at most, the entire colony will die out.
There are no replacement queens waiting in the wings in a wasp colony. New queens are only produced at the end of the summer. So if a queen dies mid-season, her colony is doomed to extinction.
Workers become aimless
When the queen dies, chaos ensues in the colony as the workers become completely aimless. The queen produces chemicals that control the behavior of the workers. Without the queen’s pheromones, the workers no longer know what tasks to perform.
Activities like foraging, nest maintenance and feeding the larvae will grind to a halt. The highly organized caste system breaks down completely. Workers wander around the nest not knowing what to do.
No more eggs are laid
With the queen gone, no more eggs are produced. Any existing larvae continue to develop into adult workers. But once these have emerged, there are no new brood to replace them.
The queen was the sole egg layer in the colony. A typical colony may have contained thousands of workers but only one queen. Her death means the end of new eggs and brood.
Fighting breaks out
As resources dwindle and new brood stops being produced, fighting often breaks out among the workers. They fight over the remaining food stores and jostle for dominance.
These fights lead to injuries and can further accelerate the decline of the colony. Wasp colonies are finely balanced systems dependent on a large worker force to function.
Workers abandon the nest
With no queen and no brood to care for, workers start to abandon the nest. They drift away in search of food and never return. The worker population steadily declines as more and more wasps depart.
Other predators like ants or parasitic wasps may attack the weakened colony and take over the nest. The abandoned nest soon becomes empty as the last workers vacate.
New queens disperse
If the queen dies late enough in summer, some new queens may have been produced. These virgin queens will disperse from the colony to mate and hibernate over winter.
The new queens do not try to take over the existing colony. Their only focus is to mate, find a suitable hibernation spot and survive the winter. Next spring, the mated queens will attempt to found new colonies of their own.
The nest deteriorates
With no wasps maintaining it, the abandoned nest quickly falls into disrepair. Nests are intricate structures made of chewed wood fiber. They require constant maintenance and patching by workers to remain intact.
Soon after the last wasps depart, the unoccupied nest starts to disintegrate. Holes form, walls collapse and papers layers peel away. Nest interiors become exposed to the elements. Over winter, the remnants of the nest get washed away by rain and wind.
Scavengers move in
The vacant nest becomes a target for scavengers looking for an easy meal. Ants invade to steal stored food and eggs. Parasitic wasps poke around looking to lay eggs. Beetles move in to eat debris.
Rodents like mice and squirrels may tear into the nest structure to make off with larvae and pupae to eat. Within weeks, all the edible parts of the nest are consumed.
Takeover by usurpers
If enough workers remain for a short time after the queen dies, the nest may get taken over by usurpers. In some species like yellowjackets, workers from neighboring colonies can invade and seize control.
These usurpers steal the brood, food stores and nest structure. If new queens happen to be present, the usurpers may kill them. The nest continues to be used but the original colony and lineage is wiped out.
Nest sites get reused
Prime nesting spots in structures, trees or underground are valuable real estate. After an abandoned nest disintegrates over winter, these cavities often get reused the following spring.
Searching queens will check out established nest sites. If the cavity is large enough, a queen may choose to start her colony there. The remains of the previous nest get cleaned out and rebuilt.
Collapse of wasp colonies
To summarize, here is what typically happens when a wasp queen dies unexpectedly:
- The colony collapses and cannot survive for long without her
- Workers become disorganized and stop their usual tasks
- No new eggs are laid so the population dwindles
- Fighting breaks out among workers
- Workers abandon the nest
- Any new queens depart to mate and hibernate
- The nest deteriorates from lack of maintenance
- Scavengers move in and clean out remnants
- In some cases, neighboring colonies may usurp the nest
- The nest site may get reused next year by a new queen
The queen is the heart of a wasp colony. When she dies, the colony has no choice but to collapse. Her offspring carry on for a short time before dispersing or dying off. Within a couple of months, all traces of the former colony disappear.
Causes of queen death
Why do wasp queens die unexpectedly during the season? Here are some of the main reasons wasp queens perish before fall:
Predators
Queens can fall victim to predators like birds, spiders, mantids and robber flies. Predators may sneak into the nest and attack the queen while she is laying eggs.
Disease
Bacterial, fungal and viral diseases can infect the queen and eventually kill her. Nosema is a common fungal disease in wasps that affects queens.
Pesticides
Pesticide sprays aimed at nests often kill queens. The queen’s death is usually unintentional, as the pest control objective is to exterminate workers.
Colony decline
As colonies naturally decline late in summer, queens may fail to survive this strenuous period. Weakened queens often die from stress and old age.
Accidents
Freak accidents happen, like a queen getting trapped in a collapsed nest cavity or caught in a spider web. These accidents can injure or kill a queen.
Worker revolt
In rare cases, workers may turn on a poorly performing queen and kill her. This usually only happens if the queen is diseased or egg production has severely declined.
Strong healthy queens are rarely murdered by their workers. But weak queens may get assassinated to pave the way for a replacement.
Impacts of queen loss
When a wasp queen dies prematurely, what are the wider ecological impacts on the local environment?
Decline of wasp numbers
Local wasp populations take a hit from the loss of a colony. Hundreds to thousands of workers, plus all their potential offspring, are removed from the area’s wasp population.
Reduction in pest control
Wasps are major predators of pest insects. Fewer wasps mean less natural biocontrol of pests like caterpillars, flies and beetle larvae.
More plant damage
With fewer wasps to prey on them, insect pest numbers may explode. This can lead to increased damage to gardens, crops and trees by uncontrolled pests.
Loss of scavengers
Wasps are also important scavengers. Lower wasp numbers make it take longer to clean up animal carcasses and other organic waste.
Reduced food for scavengers
The abandoned wasp nest itself provides an abundant food source for many scavengers when colonies collapse. Loss of wasp nests reduces available food for rat, mice, beetles and other scavenging species.
Lower pollination
Though not their main role, wasps do pollinate flowers to some extent while foraging for nectar. Declining wasp populations may negatively impact pollination of certain plant species.
Overall, local ecosystems depend on wasps performing functions like pest control, carrion cleanup and occasional pollination. When wasp numbers take a hit, these services decline which can have cascading effects.
New queens and colonies
While the colony dies out after queen loss, the wasp lineage lives on through any new queens produced. Here is what happens with the next generation:
Mating flights
In late summer and fall, new queens take mating flights. They mate with males who soon die after mating. The queens store up sperm to fertilize eggs over winter.
Hibernation
After mating, queens search for protected places to spend the winter. Common overwintering sites include hollow trees, under bark or in leaf litter or soil.
Founding new nests
The following spring, queens emerge and look to start new nests. Each queen attempts to found a colony on her own. She builds a small starter nest and begins raising her first batch of workers.
Expanding colonies
As the first workers mature, they take over nest expansion and maintenance. The queen then focuses fully on egg laying. With more workers, the colony grows rapidly over the summer.
Producing new queens
Mature, large colonies produce new queens and males in late summer. These virgin queens fly off, mate and hibernate to start the cycle over next spring. Successful colonies can thus continue for many years by constantly generating new queens.
So even when a specific colony dies, the wasp lineage endures if new queens have been successfully produced. These young queens carry their colony’s genetic line into future generations by founding new nests the following year.
Survival of wasp species
Even with the occasional local extinction of colonies, wasp species as a whole easily survive the regular death of queens. Here’s why wasp populations bounce back:
Short generation time
Wasps have a short one-year lifecycle. Nests are founded, grow, produce queens and die out within a single season. This allows populations to rebuild rapidly year after year.
High reproductive capacity
Large colonies can produce hundreds or thousands of new queens. With so many young queens dispersing each fall, wasp populations quickly rebound the next spring.
Generalist predators
Most species are generalist predators and scavengers not reliant on any one food source. This versatility allows them to thrive in most habitats.
Abundant small insect prey
Small insects like flies, aphids and caterpillars are always plentiful for wasps to prey on. There is no shortage of food sources.
Nest site flexibility
Wasps are flexible in where they build nests and can occupy diverse sites. This habitat flexibility enables queens to found nests across a wide range of settings.
Large geographic ranges
Common species have very extensive geographic distributions. Local declines are offset by populations elsewhere within the wide range.
Thanks to these traits, wasp species are very resilient to local loss of colonies. New queens easily recolonize areas where nests have died off over winter. Within a few years at most, wasp numbers are back to normal levels in the area.
Preventing premature queen death
Premature queen death can be minimized through some simple actions:
- Avoid excessive pesticide use which can kill queens
- Properly treat beehives for disease to prevent spread to wasps
- Seal holes and cracks in structures that allow access to queens
- Reduce nest disturbances which stress queens
- Plant flowering plants to provide nectar and improve queen health
- Leave some fallen trees and vegetation which provide nesting sites
- Use baits and traps rather than spraying nests directly
While occasional queen loss is normal, excessive mortality can temporarily depress local wasp numbers. Simple conservation measures can help reduce premature queen deaths and maintain healthy wasp populations.
Conclusion
Wasps colonies are intricately organized around their central queen. When she dies unexpectedly, the workers are thrown into disarray and the colony soon collapses. The abandoned nest gets cleaned out by scavengers over winter.
But if new queens have been produced, the wasp lineage survives through these virgin queens starting their own nests the next spring. Species as a whole are resilient to local queen loss thanks to their biology and adaptability.
While the death of their queen spells the end for individual colonies, wasp populations invariably recover and bounce back in subsequent years.