Sweat bees, in the Halictidae family, are a widespread group of insects often encountered in gardens and natural landscapes. These bees are a diverse family, with nearly 4,500 species globally and over 500 species native to North America alone. They are known for their varied appearance, ranging from dull brown or black to striking metallic green or blue hues. The common name “sweat bee” stems from their distinctive behavior of seeking out human perspiration.
Adult Sweat Bee Diet
Adult sweat bees primarily eat nectar and pollen from flowering plants. Nectar provides carbohydrates for energy and daily activities. Pollen supplies essential proteins, lipids, and micronutrients for development and reproduction. Many sweat bee species are generalist foragers, visiting a diverse range of flowers, while some specialize on only a few plant species.
These bees possess specialized structures, such as short tongues for nectar collection and pollen-collecting hairs on their hind legs, to efficiently gather floral provisions. As they move from flower to flower, collecting food, sweat bees inadvertently transfer pollen, playing a significant role in pollinating many plants, including agricultural crops like alfalfa, apples, sunflowers, and watermelons. Some species perform “buzz pollination,” vibrating their flight muscles to release pollen from certain flowers.
Nourishing the Next Generation
Sweat bee larvae eat differently than adults, relying on provisions left by their mothers. After constructing a nest, often in the ground or rotting wood, a female sweat bee gathers pollen and nectar. This blend forms “bee bread” within individual brood cells. An egg is laid directly onto this bee bread, which serves as the sole food source for the larva.
Bee bread provides all necessary nutrients for the larva to grow and metamorphose into an adult bee. This nutrient-rich substance contains proteins, amino acids, carbohydrates, lipids, vitamins, and minerals, essential for larval development. The female seals the cell, ensuring the larva has a protected environment and a ready food supply until it emerges.
The “Sweat” Connection
Sweat bees are known for their attraction to human and animal perspiration, which gives them their common name. They are attracted to salts and minerals, such as sodium, often scarce in their nectar and pollen diet. Human sweat, rich in electrolytes, provides a supplemental source of these vital nutrients.
When a sweat bee lands on skin, it seeks to absorb these salts, not to sting. While their floral diet provides energy and protein, trace minerals from sweat are crucial for physiological processes within the bee’s body. Sweat is a valuable, supplementary source of micronutrients that complements their main floral diet.