Wasps are predatory and scavenging insects, unlike bees which are primarily herbivores. This dual nature of their diet complicates the answer to what attracts them. Understanding why a wasp might investigate a brightly colored item requires examining how they visually and chemically perceive their environment.
Understanding Wasp Visual Perception
Wasps navigate their environment using two large compound eyes, which differ vastly from human eyes. These eyes are composed of thousands of tiny light-sensing units called ommatidia, which piece together a mosaic-like image. This visual system is highly effective at detecting motion, which aids in hunting prey and evading threats.
Wasps possess trichromatic vision, similar to humans, but their sensitivity is shifted along the light spectrum. They perceive light in the ultraviolet (UV), blue, and green ranges, but are relatively insensitive to red. UV light, which is invisible to humans, is prominent in the wasp’s world and helps them locate food sources. Colors that strongly reflect UV light, such as yellows and whites, therefore appear intensely visible to a foraging wasp.
The Chemical and Olfactory Triggers
While vision aids in short-range navigation, chemical and olfactory signals are the primary drivers for a wasp’s long-distance attraction. Wasps possess a highly developed sense of smell, allowing them to detect a wide array of chemical cues related to their varied diet from significant distances.
Wasp colonies require carbohydrates (sugars) for adult energy and protein for feeding their larvae. The need for sugar, especially in late summer, leads them to fermenting fruit, sugary drinks, and sweet picnic items. Research shows that volatiles emitted by fermenting sweet baits, such as acetic acid and 2-methyl-1-butanol, act as strong chemical lures.
The protein requirement draws them toward meat products, pet food, and other insects, utilizing compounds like heptyl butyrate as a powerful signal. Wasps also use chemical communication for colony defense; if threatened, they release an alarm pheromone that alerts nearby wasps and triggers an aggressive response. Additionally, strong floral or fruity perfumes can mimic natural food signals, inadvertently attracting wasps to people.
The Role of Bright Colors in Wasp Encounters
The attraction to bright colors is a case of mistaken identity rooted in the wasp’s survival instincts. Colors like yellow, white, and light blue are highly attractive because they mimic the visual appearance of flowers and ripe fruit, which are natural sources of sugar. This is especially true for colors that strongly reflect UV light, making them look like a glowing food beacon to the insect.
Wearing bright colors or using brightly patterned accessories in outdoor settings can increase the chances of a wasp investigating you for food. Colors less stimulating to a wasp’s UV-sensitive vision, such as muted greens, khaki, or beige, are a better option. Wasps cannot see the color red; they perceive it as a dark shade, making it a less attractive color for foraging.
Dark colors like black or deep blue can still pose a risk. While they do not signal food, dark, solid colors can sometimes be mistaken for a large animal or prey item by a defensive wasp, triggering an investigative or aggressive encounter. The most practical strategy is to prioritize minimizing olfactory signals, such as covering sweet drinks and food, while opting for neutral, earthy-toned clothing to reduce visual attraction.