Nature’s Artists: The World of Potter Wasps

I have been asking people what comes to their mind when they hear “wasps”. The responses were not surprising. Most said, “black and yellow, scary insects”. When I ask, “Is that it? Do you know how many different types of wasps there are?” the unanimous response is, “Aren’t they all the same, more or less?”

There are many types of wasps, each with unique behaviours and appearances. Paper wasps are known for their paper-like nests; spider wasps hunt spiders; and hornets and yellow jackets can be quite intimidating. Then, we have potter wasps, true artists in the insect world, creating beautiful, pot-like nests of mud. Unlike other wasps, potter wasps lead solitary lives, with each female responsible for constructing her own nest and caring for her offspring. Potter wasps usually feed on plant nectar and hunt live caterpillars to feed their larvae.

Worldwide, there are approximately 3,800 species (Subfamily: Eumeninae) of potter wasps (Order: Hymenoptera. Family: Vespidae.). Eumeninae is the most diverse of all subfamilies within Vespidae. In India, there are 189 potter wasps species that belong to 47 genera.

Nesting strategies: Not All Potter Wasps Make Pots

Interestingly, despite their name, not all potter wasps make pots for nests. They are renowned for exhibiting diverse nesting strategies and can be excavators, renters, or builders. Excavators dig their nests in the ground or in soft, decaying wood, creating tunnels and chambers where they lay their eggs and provision the cells with paralysed caterpillars. Renters prefer to rent pre-existing cavities like abandoned beetle burrows, hollow stems, or other natural cavities. These spaces are modified by adding mud partitions to create individual brood cells (a time- and energy-saving strategy).

Builders construct intricate mud nests that resemble tiny pots or jugs, which are often attached to twigs, rocks, or manmade structures. To create these, the wasp gathers mud and shapes it into brood cells, each carefully crafted and provisioned with caterpillars. Irrespective of the type of nest, all potter wasps exhibit remarkable nesting plasticity, adapting to various environments and utilising different materials to create secure spaces for their offspring. Some potter wasps are so versatile that they may even nest inside active termite mounds. These underground nests protect eggs from predators and harsh weather conditions. A completed potter wasp nest often has a flared entrance, which adds to its distinctive appearance. Once construction is over and the nest has dried, the mother wasp ventures out to hunt prey (usually caterpillars) and stores the paralysed prey in the cells. She then inserts her abdomen into the nest to lay an egg inside the brood cells.

Lookout for caterpillars

Potter wasps are predators, and their diet primarily consists of other insects, particularly caterpillars, spiders, and other garden and field insects. They hunt actively for prey, often capturing them midair or stalking them on plants and flowers. Once the potter wasp locates potential prey, it subdues it with a quick sting, injecting venom to immobilise its victim. However, unlike some other species of wasps that paralyse their prey completely, potter wasps often only partially paralyse their victims, allowing them to remain alive but immobile. This ensures that the prey stays fresh for the developing larvae to feed on once the eggs are laid.

The mother wasp embarks on hunting expeditions to capture live caterpillars, which she paralyses and stocks the nest. Each brood cell is provisioned with several caterpillars, ensuring the larva has a sufficient food supply once it hatches. The mother wasp tirelessly repeats this cycle, ensuring her offspring have an ample food supply once they hatch. This process of provisioning the nest can take considerable time and effort, more than that of nest-building, as the wasp must capture enough prey to feed her offspring.

After provisioning the nest with caterpillars and laying eggs subsequently, the mother potter wasp seals each brood cell and the nest, securing the provisions within. Using mud, she creates a sturdy plug at the entrance of each brood cell. Depending on the species and the season, the mother wasp may then construct additional nests, repeating the process of gathering mud, building nests, laying eggs, and provisioning the cells with caterpillars multiple times within her lifespan. She continues to forage for food, primarily nectar and other plant-based substances, to sustain her energy levels. Some mother wasps exhibit defensive behaviour around their nesting sites to protect their progeny from potential threats. Eventually, the mother wasp’s life comes to a natural end, typically coinciding with the onset of colder weather or the completion of her reproductive duties.

As the larvae hatch, they consume the stored caterpillars, sustaining their growth and development within the safety of the nest. Once the larva has consumed the provisioned caterpillars, it spins a cocoon within the brood cell and pupates. After the transformation, the adult wasp uses its strong mandibles to chew its way out of the cocoon and the nest’s mud plug. The young wasp then acclimates to its surroundings, takes its first flight, and begins its independent life, foraging for food, and eventually seeking a mate. The primary goal of adult potter wasps is to reproduce and ensure the survival of their species. Males and females typically mate shortly after emerging from their cocoons. After mating, females search for suitable nesting sites to lay their eggs and begin the lifecycle anew.

Potter wasps are essential players in maintaining ecological balance. As predators, they help control populations of pest insects like caterpillars, contributing to the health of plant communities. A word of caution before disturbing discarded potter wasp nests found in your lawn: discarded potter wasp nests serve as valuable resources in the ecosystem, often repurposed by other insects for shelter. These abandoned nests provide a ready-made structure for various species of solitary bees, beetles, or spiders, offering them protection from predators and adverse weather conditions.