Delphinium, commonly known as larkspur, is a striking ornamental garden plant recognized for its tall, colorful flower spikes. As interest in supporting local ecosystems grows, many gardeners are curious whether this popular flower provides a viable food source for pollinating insects. The answer is nuanced and depends largely on the specific type of bee attempting to forage on the flower.
Delphinium’s Specialized Appeal to Pollinators
Delphinium flowers possess a unique structure that dictates which pollinators can successfully access the nectar reward. Each flower has a prominent, hollow projection, known as a spur, where the nectar is stored deep inside the bloom. This specialized architecture acts as a mechanical filter, effectively excluding many common, short-tongued insects like the generalist honeybee.
The plant is primarily adapted for visitation by long-tongued species, especially certain types of bumblebees. These larger bees have the necessary mouthpart length to reach the nectaries at the end of the spur and are the most efficient pollinators of the plant. Bumblebees will often be seen clinging to the flowers to retrieve the sugary liquid.
Short-tongued bees, unable to reach the nectar through the intended route, sometimes resort to a behavior known as “nectar robbing.” These bees will chew a hole directly through the base of the floral spur to steal the nectar without contacting the pollen-bearing structures. While this allows them to gain a quick energy source, it bypasses the pollination process, reducing the plant’s reproductive success. This interaction creates a biological divide, making delphinium a specific, rather than universal, resource for bees.
Nectar Reward and Pollen Value
Once a bee successfully accesses the flower, the nutritional quality of the forage determines its overall value to the insect colony. Nectar serves as the primary source of carbohydrates, providing the necessary energy for flight and colony maintenance. While specific chemical analyses for delphinium nectar are not widely published, the sugar concentration is generally considered adequate for the bees that can reach it.
Pollen, the other major floral resource, provides the protein, lipids, vitamins, and minerals necessary for larval development and the production of new bees. The protein content of pollen varies widely among plant species. While delphinium pollen is collected by long-tongued bees, its protein content is not consistently ranked as a superior, high-value source. The plant is best viewed as a supplemental or secondary source of food, providing necessary diversity in the bee’s diet.
Cultivation Considerations for Bee Gardens
Gardeners wishing to incorporate delphinium while actively supporting bees should select specific cultivars to maximize accessibility. Highly hybridized varieties that feature dense, “double” flowers often impede a bee’s ability to reach the nectar and pollen structures. Choosing single-petal or “Belladonna” types, which have a more open floret, generally provides easier access for foraging insects.
Planting delphinium in large groups or drifts makes the flowers more visible and attractive to pollinators. They should be placed near other high-value forage plants to offer a diverse and consistent food supply throughout the season. Gardeners should also be mindful of pesticide use, especially since delphinium is a prominent ornamental.
Systemic pesticides, which are absorbed into the plant’s tissues and expressed in the nectar and pollen, can harm foraging bees. Avoiding these chemicals is important to creating a safe foraging environment. Using non-chemical methods or targeted, pollinator-safe treatments for common pests helps ensure the flowers remain a healthy resource.