Eucera longicornis, or long-horned bees, are a unique species of solitary bee.
They belong to the same family (Apidae) as honey bees, bumblebees, carpenter bees, and others with the two major genera Eucera and Melissodes.
Long-horned bees were once found in vast populations throughout North America and even Southern Britain. However, the numbers of Eucera longicornis have dwindled significantly over time. This is due to changes in their habitats such as deforestation, degradation, and other environmental factors.
There are over 200 species of Eucerini (longhorn bees) in North America and North Mexico. Sightings in Central and South America are rare. In Britain, a recorded total of 629 sightings from 1800 to 2021 are confirmed. These bees exist in only about two dozen sites along the south coast. This makes sightings at inland locations extremely uncommon.
Continuous local and national conservation efforts are in place to help protect this species from further decline and extinction. These include preserving existing habitats and creating new ones. Along with habitat protection and restoration initiatives, educational programs to raise awareness amongst the public are important.
The body of this species has a robust composition. It is usually in black and yellow, with three contrasting stripes running down the back.
The male Long-horned bee has an exceptionally long antennae that can grow up to one inch in length. Their thorax and abdomens are covered with light brown hair that can fade to a silvery white when exposed to the sun. Many males as well as females have yellow faces.
Females are similar to males but with a shorter antennae. Compared with their male counterparts they are slightly sturdier and have a more robust frame. Females are sometimes confused with Flower bees of the Anthophora species.
Long-horned bees do not produce honey. Only females have a stinger and although they are not aggressive as such, they do sting when threatened.
The Eucera longicornis also serves as host to the rare six-banded nomad bee (Nomada sexfasciata) that is classified as ´Critically Endangered´ in Britain. The N. sexfasciata is a cleptoparasite of the Eucera longicornis and depends on strong populations of its host. According to a 2020 survey, the N. sexfasciata is confined to a single site on the South Devon Coast of Britain.
Long-horned bees are particularly adept at finding sources of nectar and pollen, enabling them to sustain themselves over long periods of time. These bees typically feed on flowers of the narrow-leaved everlasting pea (Lathyrus sylvestris), clovers, and Bird’s foot trefoil (Lotus corniculatus). Other plants to sustain this species include vetches like the common vetch (Vicia sativa), Kidney vetch (Anthyllis vulneraria), narrow-leaved everlasting pea (Lathyrus sylvestris) and Meadow vetchling (Lathyrus pratensis) (Saunders, 2018).
Although they prefer open expanses with abundant flowering plants, they can also be found in more urbanized areas with carefully managed flower gardens and plantations. In addition to nectar and pollen, these bees consume certain types of fruit juices, as well as several other substances such as tree sap and honeydew excreted by aphids.
Long-horned Bees Nesting Preferences
Bees of this species are commonly seen in coastal grasslands, soft cliff faces, heathland edges, woodland rides, clearings and brownfield sites. These areas provide them with the necessary conditions for nesting and finding the flowers they need to feed on.
Long-horned bees nest in cavities found in trees and shrubs, in natural or artificial holes, or under tree bark. Bees of this species help pollinate agricultural crops such as apples, pears and strawberries when they visit these fields. Consequently, these industrious bees contribute to the health of both wildflower meadows and crop fields alike.
In May, adult Long-horned bees come out to forage, which generally lasts until early July. These solitary bees construct their own nests in exposed or scantily vegetated surfaces, usually on south-facing slopes or clifftops.
Although they prefer to nest alone, it is not uncommon to nest in aggregations like mining bees. Their burrows are created with precision and finesse, dug deep into the ground with utmost care and attention to detail.
Female Long-horned bees have an interesting habit of collecting bits of soil and carrying them outside the burrow while they excavate. This allows them to build up small mounds around the exterior of their nests. When not actively foraging, these industrious insects fortify their dwellings with plant material such as leaves and grasses, giving further protection from the elements.
Moreover, many species also carefully line their burrows with waxy secretions produced by specialized glands located on their abdomens. This wax helps to water-proof their brood and keeps the nest cool during hot summer days and provides insulation during colder months.
Reasons for the Decline of the Long horned Bees
The Long-horned bee is facing a major threat due to its dwindling habitat, which has seen an alarming 97% loss over the course of the 20th century. The reasons for this are a combination of overgrazing, poor management of grassland and coastal development causing cliff stabilization.
Male Long-horned bees can easily be deceived by Bee orchids (Ophrys species). These fascinating flowers have an uncanny resemblance to the bees in terms of size, color and shape. Interestingly, they also produce pheromones. These are so convincing that some males think they are a potential mate. These orchids are a unique example of the power of mimicry as a survival mechanism. By fooling male bees, they can easily be pollinated and their species preserved. This interesting fact shows that nature is full of ingenious tricks to ensure its survival in the face of changing conditions.