Yellow jackets are social wasps known for their distinct yellow and black markings. While they are active predators of other insects, their tendency to scavenge near human activity, especially later in the summer, often causes concern. They can sting repeatedly and become aggressive when their nest is threatened. Understanding the specific cues that attract these insects is important for safely minimizing encounters and reducing the risk of a painful sting.
Yellow Jackets and Light: A Direct Answer
Yellow jackets are diurnal insects, meaning their primary activity cycle occurs during the daytime. They forage for food and water mostly between 10:00 A.M. and 4:00 P.M. This day-active nature means they do not rely on artificial light sources for navigation or foraging. Consequently, yellow jackets typically exhibit little to no positive phototaxis, which is the instinctive movement toward a light source.
Artificial lights, particularly those emitting blue or ultraviolet (UV) wavelengths, are far more attractive to insects that navigate by the moon or stars. Yellow jackets are generally not drawn to porch lights or yard lights. While a stray yellow jacket might occasionally be seen near a light at night, this is not a common or sustained foraging behavior. Their nighttime presence is usually an incidental event, as their colonies are mostly inactive after dark.
Primary Attractants: What Yellow Jackets Truly Seek
The true drivers of yellow jacket attraction are specific chemical and olfactory cues related to food sources, not light. As scavengers, they are highly attuned to strong sweet and savory smells, which often leads to conflict during human outdoor activities. Their diet shifts throughout the colony’s life cycle, causing them to seek different nutrients at various times of the year.
In the late summer and early fall, yellow jackets aggressively seek carbohydrates, or sugars, to fuel their large and rapidly expanding colonies. This attraction translates to spilled sodas, fruit juices, ripe fruit, and sugary desserts. The fermentation process in these sugary substances releases compounds like isobutanol and acetic acid, which are powerful attractants for many species, including the German and Eastern yellow jackets.
In addition to sugars, yellow jackets also require protein to feed the developing larvae back at the nest. This need makes them seek out meat products, pet food, and picnic scraps, particularly during mid-season. The volatile chemicals they seek, such as acetic acid and isobutanol, are often used in commercial yellow jacket traps. Different species also respond to other chemical attractants like heptyl butyrate, confirming their focus on food odors rather than visual light cues.
Practical Strategies for Minimizing Encounters
Since yellow jackets are primarily drawn by odors, managing food and waste is the most effective preventative strategy. When eating outdoors, keep all food and drinks covered, especially sweet beverages and meat dishes. Immediately cleaning up any spills removes the chemical signals that attract foraging wasps to the area.
Proper waste management significantly reduces the availability of yellow jacket food sources. Outdoor garbage cans and recycling bins must have tight-fitting lids and be emptied frequently. Placing these receptacles away from high-traffic areas, like patios or doorways, helps redirect foraging activity away from people. Sealing potential nesting sites, such as cracks in walls or gaps in siding, also reduces the overall presence of colonies near human dwellings.