Primary Food Sources
Wasps, particularly common social species like Yellowjackets and hornets, are strongly attracted to specific food sources. Their diet is split into two categories: high-energy carbohydrates, which fuel adult workers, and protein, which is necessary for the growth of the developing brood. This duality means that outdoor dining areas often contain everything a foraging worker needs.
Protein is sought by workers during the spring and early summer months to feed the thousands of larvae back at the nest. These sources include scavenged meat, fish scraps, carrion, and exposed outdoor pet food. Yellowjackets are proficient scavengers, often seen attempting to slice off pieces of hot dogs or hamburgers at picnics to bring back to the young.
Adult wasps cannot digest solid protein themselves and rely entirely on carbohydrates for flight and energy. They seek out readily available sugars from sources like fruit nectar, tree sap, spilled sodas, and fermented fruit that has fallen to the ground. The need for these sugars is present throughout the season, but the urgency with which adults seek them changes dramatically as the colony progresses through its annual cycle.
Non-Dietary Environmental Cues
Attraction to human environments is not solely driven by the need for sustenance; wasps are also drawn in by sensory and habitat cues. Strong, sweet-smelling odors, such as those emanating from perfumes, heavily fragranced soaps, or scented body lotions, can easily confuse foraging workers. These artificial floral scents mimic the chemical compounds of flowering plants and nectar sources, drawing wasps to the person wearing them.
Visual stimuli also play a significant role in initial attraction, as wasps rely on sight to locate food and flowers. Bright colors, particularly yellow, white, and orange, along with clothing featuring busy, floral-like patterns, can be mistaken for a food source from a distance. The visual appearance of clothing can unintentionally signal a potential reward, causing a worker to investigate more closely.
The availability of resources for nest maintenance and temperature regulation is a powerful attractant. Wasps require a consistent water source for drinking, cooling the nest, and mixing with wood fibers to create the paper-like nest material. Leaky outdoor hoses, dripping faucets, standing water in bird baths, and pools draw workers looking to collect moisture. Sheltered locations like eaves, accessible wall voids, sheds, and holes in the ground provide the necessary dark, dry, and protected spaces for queens to establish a new colony.
The Role of the Wasp Life Cycle
The intensity of interaction between wasps and humans is governed by the colony’s annual life cycle, which dictates what resources the workers prioritize. In the spring, a single queen emerges from hibernation and begins building a small nest, laying eggs that develop into the first sterile female workers. During the early and mid-summer, the colony’s primary focus is growth, requiring workers to forage for protein to feed the thousands of developing larvae.
The larvae secrete a sweet, carbohydrate-rich saliva that the adult workers consume. This larval secretion provides the adult workers with their internal source of sugar energy, allowing them to focus their external foraging efforts almost entirely on protein. The colony population expands rapidly throughout the summer, reaching its maximum size by late summer or early fall.
This dynamic changes when the larvae mature, pupate, and stop producing the sugary saliva. The large, active adult population, now cut off from its internal sugar supply, must switch to aggressively foraging for external carbohydrates for energy. This shift coincides with the late summer and fall months, explaining why adult wasps suddenly seem much more numerous, persistent, and attracted to human sources of sugar, like sodas, fruit, and picnic foods.
Reducing Attraction Risks
Managing the presence of wasps involves proactively removing or mitigating the specific attractants that draw them into human areas. A primary action is ensuring that all food sources, especially sweet liquids and proteins, are inaccessible outdoors. This means sealing outdoor trash cans with tight-fitting lids, covering drinks and food when dining outside, and immediately cleaning up any spills of sugary beverages or fruit juices.
Addressing non-dietary cues requires attention to personal products and environmental design. When spending extended time outdoors, one can reduce attraction risks by avoiding heavily scented personal care items, such as floral perfumes or body sprays. Opting for clothing in neutral or muted colors, rather than bright yellows or busy floral patterns, can also make a person less visually appealing to a foraging wasp.
Mitigating habitat and water sources further reduces the likelihood of attraction. It is helpful to repair leaky outdoor plumbing and remove sources of standing water, such as buckets or clogged gutters, which wasps use for hydration and nest construction. Sealing exterior cracks, crevices, and holes in the ground or structures can prevent queens from establishing new nests near human activity.