Yellow jackets are a common sight, especially during late summer and into the fall. While they can exhibit aggressive behaviors, this is typically in response to specific circumstances, driven by self-preservation and the protection of their colony and food sources.
Understanding Yellow Jacket Behavior
Yellow jackets are social wasps that live in colonies, which can grow to contain thousands of individuals by late summer. Throughout much of the summer, these wasps act as beneficial predators, hunting other insects like caterpillars and flies to feed their larvae.
As the season progresses into late summer and fall, colony dynamics and dietary needs shift. The queen stops laying eggs, reducing the demand for protein for larvae. Adult yellow jackets then seek sugary substances for energy, such as ripe fruits, nectar, and human foods. This dietary change, coupled with peak colony population, leads to increased scavenging and territoriality.
Common Triggers for Aggression
Yellow jackets are protective of their nests and food sources. Disturbing their nest, even accidentally, is a primary trigger for them to sting. Ground vibrations, such as those from mowing a lawn, can also trigger a defensive swarm attack from underground nests.
Competition for food, particularly sugary items like soda, fruit, and uncovered picnic foods, is a frequent cause of aggressive encounters. Yellow jackets are drawn to these sweet scents and will vigorously defend access to them.
Sudden movements or swatting at a yellow jacket can be perceived as a threat, prompting them to sting. Strong scents from perfumes or sweet-smelling body products can attract them, increasing the likelihood of an encounter.
Identifying Yellow Jackets and Preventing Encounters
Yellow jackets are often mistaken for bees. They possess a smooth, slender body with bright yellow and black stripes and a narrow waist between their thorax and abdomen. Unlike bees, which are hairier and have flattened hind legs for carrying pollen, yellow jackets are hairless. A worker yellow jacket is about 12 mm (0.47 inches) long.
To prevent encounters, keep outdoor food and drinks covered, especially sugary items, and dispose of trash promptly in sealed containers. Avoiding strong perfumes, scented lotions, or bright colors can reduce attraction. Regularly inspecting outdoor areas for nests, particularly in the ground, in hollow logs, or under eaves, and sealing cracks in structures can deter them from nesting nearby.
Responding to an Encounter
If a yellow jacket is nearby or appears aggressive, remaining calm is important. Avoid sudden movements or swatting, as this can provoke them to sting and cause them to release a pheromone that alerts other yellow jackets to attack. Instead, slowly back away from the area. If you have disturbed a nest, move quickly and directly away.
If stung, yellow jackets can sting repeatedly as their stingers do not have barbs and do not detach. For a mild reaction, wash the area with soap and water, apply ice to reduce pain and swelling, and consider an antihistamine for itching. If an allergic reaction occurs, characterized by difficulty breathing, swelling of the face or throat, hives, or dizziness, seek immediate medical attention.