The mating behavior of wasps is often misunderstood. Many people assume that in a wasp colony, only the queen mates and produces offspring. However, the reality is more complex. In most species of social wasps, the queens do the majority of the mating and egg-laying. But in some cases, other female worker wasps are also able to mate and lay eggs that become viable offspring. So in short, no, wasps do not only mate with the queen.
An Overview of Wasp Mating
In a typical wasp colony, the queen is the primary female reproductive. She mates with male wasps, who are known as drones. The drones die shortly after mating. The queen then builds a nest and lays fertilized eggs that hatch into female worker wasps. The workers care for the larvae, build and defend the nest, and gather food.
Later in the season, the queen lays unfertilized eggs that become male drones. She also lays fertilized eggs that develop into new queens. The new queens and drones leave the colony to mate. The drones die after mating, while the mated queens overwinter to start new colonies in the spring.
This cycle continues, with the queen producing workers in the early part of the season and reproductive wasps later in the season. The workers are generally sterile and cannot mate or lay eggs. Only the queen reproduces. But there are some exceptions.
Worker Egg Laying in Some Species
In most wasp species, the workers are completely sterile due to their physiology. However, in some types of wasps, the workers retain some ovarian function and are able to mate and lay eggs. These species include:
- Paper wasps
- Polistes dominula
- Vespula squamosa
- Vespula vulgaris
In these species, worker-laid eggs may account for up to 20% of the eggs in a colony. The workers generally sneak matings with males when the queen is not present. They lay the fertilized eggs in nest cells, though many of these eggs do not survive to adulthood. In other cases, the worker-laid eggs are cared for by their sisters and develop into adult wasps.
Researchers believe worker mating evolved because it increases genetic diversity in the colony. It may also act as a reproductive insurance policy if the queen dies. While the queen still does the vast majority of the reproducing, the mating flexibility of workers supplements her output in some species.
Factors That Influence Worker Reproduction
Several factors influence the rates of worker mating and egg laying in wasp colonies:
Queen Presence and Age
Workers are less likely to lay eggs when the queen is present and young. As the queen ages and loses dominance, worker reproduction increases. Removing the queen from a colony also stimulates worker egg laying.
Smaller colonies tend to have higher rates of worker reproduction. When there are fewer workers to share reproduction with the queen, the workers are more likely to activate their ovaries and lay eggs.
When food is scarce, worker egg laying increases. The workers may take the opportunity to reproduce for themselves when the colony’s survival appears uncertain.
Worker reproduction occurs more often later in the nesting cycle, when male reproductives are being produced. This gives the workers a chance to mate with the males.
Colonies with higher genetic diversity due to multiple founding queens tend to have increased worker reproduction. Again, this adds even more diversity to the colony’s makeup.
So in species where worker reproduction is possible, it tends to occur under conditions of queen absence, small colony size, limited food, and late nest stage. The workers opportunistically lay eggs, though their reproduction is dwarfed by that of the queen.
Outcomes of Worker Reproduction
What happens to the offspring when wasp workers do manage to mate and lay eggs? There are a few possible outcomes:
- Many eggs fail to hatch.
- Some larvae are killed by other workers.
- Some males reach adulthood but are expelled from the colony.
- A small number of males and females survive in the colony.
Again, the reproductive success of worker-laid eggs is very low compared to the queen’s eggs. But worker mating does occasionally boost the colony’s numbers and genetic diversity.
Interestingly, one study even found that worker-laid eggs are more likely to survive in colonies with a younger, less dominant queen. The aging queen loses some control, allowing more worker offspring to be reared.
Do Workers Lay Eggs in Other Wasp Species?
While several wasp species exhibit flexible mating and egg laying by workers, many do not.
In hornets, yellowjackets, and some paper wasps, workers retain functioning ovaries but rarely mate or lay eggs. Part of this may relate to queen control through pheromones and aggressive behavior.
In other species, the workers are sterile and lack reproductive organs entirely. This group includes:
- Umbrella wasps
- Potter wasps
- Spider wasps
- Cicada killer wasps
The sterile workers have no ability to mate or lay eggs at all. This leads to more colony cohesion, as the queen has total reproductive dominance. But the cost is less genetic diversity. Different wasp lifestyles may favor either strict queen control or reproductive flexibility.
Wasp Mating Habits Compared to Bees
The wasp mating systems can also be compared to bees, which show some similarities and differences:
- The queen does all the mating and egg laying.
- Workers cannot mate or reproduce.
- Males die shortly after mating.
This strict division of reproduction is similar to highly eusocial wasp species.
- Early in the season, the queen does all the mating and egg laying.
- As the queen’s control weakens, workers may lay unfertilized eggs that become males.
- Some mating by new queens also occurs late in the colony cycle.
This pattern is more similar to wasps that allow some worker reproduction, though bumble bee workers cannot produce female offspring.
So bee reproductive strategies have some parallels with wasp strategies, depending on the species. But wasps exhibit a wider range of reproductive behaviors, from total queen control to significant worker mating flexibility.
While the queen is the primary reproductive female in wasp colonies, some wasp species do allow worker mating and egg laying. Under certain conditions, workers may reproduce to boost colony numbers and genetic diversity. However, the queen does the vast majority of mating and reproducing overall. So in a sense, wasps demonstrate conditional flexibility when it comes to the question of who mates and reproduces. The queen remains dominant, but workers get some reproductive opportunities in certain situations. This blend of queen control and worker participation may represent an optimal balance for certain species of social wasps.