Wasps

Wasps belong to the insect order Hymenoptera, which also includes bees and ants. Australia is home to many different wasp species, ranging from solitary wasps that live and hunt independently to social species that establish colonies containing numerous individuals. Wasps can be beneficial because many species prey on other insects and their larvae. However, social wasps can become a pest when they establish nests around homes, workplaces and areas regularly occupied by people. Depending on the species, nests may be constructed from paper-like material or mud, or established underground, within tree hollows, wall cavities, roof voids and other protected locations.

Wasps vary considerably in size, colour and appearance depending on the species. Most have two pairs of wings, well-developed antennae and a distinct division between the thorax and abdomen. Many species have a noticeably narrow waist. Paper wasps commonly have relatively slender bodies with long legs that can be visible hanging beneath them during flight. Their nests generally consist of exposed paper-like cells. European wasps are more robust and have distinctive yellow and black markings. Workers are approximately 12–16 mm long, while queens are larger. Correct identification can be important because nesting behaviour, colony structure and appropriate management methods vary between wasp species.

Wasps undergo complete metamorphosis through four life stages: Egg → Larva → Pupa → Adult In social wasp colonies, a queen establishes the nest and lays eggs within individual cells. The developing larvae are cared for by adult wasps until they pupate and eventually emerge as adults. As the colony develops, workers take over activities such as nest construction, collecting food, caring for developing larvae and defending the nest. Colony size and seasonal development vary considerably between species. European wasp colonies generally develop through the warmer months. New queens and males are produced as the colony matures. Fertilised queens can survive the colder period and establish new colonies when suitable conditions return. In favourable conditions, some colonies may persist for longer than a single season.

Wasps are generally most active during daylight hours and may be seen searching for food, collecting nesting material or travelling between their nest and surrounding areas. Different species have very different nesting habits. Paper wasps commonly construct exposed nests beneath eaves, awnings, pergolas, outdoor furniture, fences, branches and other sheltered locations. Other species may construct mud nests on walls or protected surfaces. European wasps commonly establish concealed nests underground or within protected locations such as wall cavities, roof voids, tree stumps and rockeries. Wasps may be attracted to food and sugary substances, particularly around outdoor eating areas, rubbish bins and food-handling environments. Social wasps can defend their nest when they perceive a threat. Activity around a nest should therefore be approached cautiously and unnecessary disturbance avoided.

Wasps can become a significant problem when nests are established close to homes, workplaces, pathways, entrances, outdoor entertaining areas or other places where people regularly pass. Some wasp species can sting more than once. Stings can be painful and may cause local swelling and irritation. More seriously, some people can experience a severe allergic reaction to wasp venom. A severe systemic allergic reaction (anaphylaxis) is a medical emergency. Wasps entering drink cans, bottles or other food and drink containers can also create a particular risk because a sting inside the mouth or throat may cause significant swelling. The risk generally increases when a nest is disturbed or when people unknowingly approach an active nesting site.

Effective wasp management begins with identifying the species involved, locating the nest where possible and assessing its position and the potential risk to people using the surrounding area. Not every wasp seen around a property indicates that a nest is present on the property. Wasps may travel some distance while searching for food and other resources. Where a nest presents a risk, professional management may be required. Professional Pest Management Professional wasp management begins with assessing the wasp activity and, where possible, identifying the species and locating the nest. The appropriate management method will depend on the species involved, the location and accessibility of the nest, the level of activity and surrounding site conditions. Treatment methods may include appropriately selected professional insecticidal treatments applied to the nest, nest entrance or other areas of activity. Dusts, foams or other suitable treatment methods may be used depending on the circumstances. Exposed paper or mud nests may sometimes be removed following appropriate treatment where this can be done safely and is considered necessary. Concealed nests within wall cavities, roof spaces, underground areas or other inaccessible locations may require a different approach. Because wasps may defend their nest aggressively, active nests should not be unnecessarily disturbed. Prevention & Non-Chemical Risk Management Reducing conditions that attract wasps can help minimise activity around homes and businesses. Food scraps, sugary drinks and other food sources should be cleaned up promptly, particularly around outdoor eating and entertaining areas. Rubbish bins should be kept closed and food waste appropriately contained. Drink cans and bottles should be checked before drinking when wasps are active nearby. Gaps and openings that may allow wasps to enter roof spaces, wall cavities or other parts of a building can be repaired or sealed where appropriate. However, openings associated with an active concealed nest should not simply be sealed while wasps are still using them, as this may cause wasps to seek another route. Regularly checking sheltered areas such as eaves, pergolas, sheds and other structures may help identify developing nests before they become larger.

Signs that a wasp nest may be present include: * Repeated wasp activity around the same location * Wasps regularly entering and leaving a hole or opening * A visible paper or mud nest * Increased numbers of wasps around a building or outdoor area * Wasps entering roof spaces, wall cavities or other structural openings A steady stream of wasps travelling to and from the same location can indicate a nearby nest. If an active nest is discovered, avoid unnecessary disturbance and keep people and pets away from the immediate area until it can be assessed.