Clover is a highly effective attractant for a wide variety of bees, establishing itself as a significant forage source in many ecosystems. This common plant, often found in lawns and pastures globally, provides an abundant food supply for numerous pollinator species. Its widespread distribution and prolonged flowering period make it a reliable resource for bees throughout the summer months. The relationship between bees and clover is mutualistic: bees gain sustenance, and the plant secures the necessary pollination for seed production.
The Primary Attractants in Clover Flowers
The success of clover as a bee magnet is rooted in its floral chemistry and physical structure. Clover flowers grow in dense, spherical clusters known as heads, offering a high reward-to-effort ratio for foraging insects. A bee can land on a single flower head and access dozens of individual florets quickly, maximizing the amount of nectar collected per trip. This clustered arrangement makes foraging highly efficient compared to plants with scattered blooms.
The primary incentive for a bee is the nectar, a sugary solution that provides the energy necessary for flight and colony maintenance. Clover nectar has a high sugar concentration, making it a valuable energy source, but its accessibility depends on environmental factors. For example, in white clover (Trifolium repens), the nectar must rise sufficiently within the corolla tube to be reached by the relatively short tongue of the honey bee. This requires specific conditions, often warm temperatures above 20 degrees Celsius, ensuring the nectar is readily available.
Beyond the sweet reward, volatile organic compounds (VOCs) emitted by the flowers act as olfactory signals guiding bees to the food source. In white clover, two volatile compounds identified are 2-propanone and 2-butanone, which are unique to that species’ scent profile. Additionally, the compounds (E)-3-hexenyl acetate and (E)-3-hexenol are present in the scents of white, red, and strawberry clovers, with white clover emitting them in substantially larger quantities. These chemical cues allow bees to identify and locate a clover patch from a distance.
Clover Varieties and Bee Visitation Rates
The degree to which different clover species attract bees is influenced by their distinct flower morphology. The most common variety, White Clover (Trifolium repens), possesses a shallow corolla tube. This short structure makes the nectar easily accessible to generalist pollinators, including the European honey bee (Apis mellifera) and many smaller native bee species. White clover is a major contributor to honey production globally and is frequently visited by a broad spectrum of short-tongued insects.
In contrast, Red Clover (Trifolium pratense) presents a specialized challenge for pollinators due to its deeper corolla tube. The nectar is often too deep for the short proboscis of the honey bee to reach. This physical barrier limits successful foraging on red clover mainly to long-tongued insects, such as large bumblebee species.
The difference in corolla depth explains why a field of red clover may appear to have fewer honey bees but a high concentration of bumblebees. Other varieties, like Crimson Clover (Trifolium incarnatum), also have deeper florets, which are less preferred by honey bees than the more accessible white clover. The physical dimensions of the flower determine the specific bee species that can successfully access the reward.
The Role of Clover in the Bee Diet
Clover provides a balanced nutritional profile, offering both the carbohydrates needed for energy and the protein required for growth. The nectar, primarily a sugar solution, serves as the colony’s main source of carbohydrates, fueling the adult bees and being converted into honey for storage. Clover honey is prized for its light color and mild, delicate flavor profile.
The pollen gathered from clover flowers is rich in protein, which is necessary for feeding developing larvae. This protein source contains a balance of amino acids that support the physiological development of the bees. Beyond macro-nutrients, clover pollen also contains beneficial secondary metabolites, such as p-coumaric acid. This compound has been linked to improving the gut health of honey bees.
As a widespread and resilient plant, clover often blooms from late spring through the summer, acting as a reliable food source when other floral resources might be temporarily scarce. This continuous supply of high-quality nectar and pollen supports colony health and stability throughout the warmer months.