Box-Headed Blood Bee

The box-headed blood bee (Sphecodes monilicornis) is a species of sweat bee that is native to Europe but now lives in Asia and North Africa, too. Sphecodes monilicornis is a small to medium-sized bee species that belongs to the family Halictidae, which contains approximately 4,500 species; 500 of those species are sweat bees. The cosmopolitan genus Sphecodes accounts for approximately 120 of them. Sweat bees are referred to as such due to their attraction to perspiration, which offers them moisture and salts. Sweat bees, like the box-headed blood bee, are on the small side, and are never aggressive toward humans. However, they are obligate kleptoparasites that deposit their eggs in the nests of other sweat bee species, often destroying any host eggs and/or larvae in the process. Keep reading to learn more about these temperamental insects.

Five Facts about Box-Headed Blood Bees

• Box-headed blood bees are attracted to perspiration
• They are obligate kleptoparasites
• Box-headed blood queen bees deposit their eggs in subterranean host brood cells
• They have red abdomens.
• Box-headed blood bees are a species of sweat bee.

Scientific Name

The name Sphecodes monilicornis is the Latin binomial name for the box-headed blood bee. The first part of the name, Sphecodes is the genus name and refers to a group of closely related species. The second part of the name, monilicornis, is specific and unique to a particular species within the genus. In this case, monilicornis translates as a single horn. Some individuals in the species have a single horn on their heads, though not all box-headed blood bees do.

Box-Headed Blood Bee: Appearance

Box-headed blood bees are small-to-medium-sized sweat bees. Their bodies measure between 0.25 – 0.75 inches (6.35 – 20 mm) long, with similarly sized wingspans. These bees have slender shiny dark brown to black heads and thoraxes, with distinctive blood-red abdomens, though in the smaller males, the red is not as visible. Females are distinctive for their box-shaped heads., and sparse,light hair on their hind legs. They may have a single horn on their head, which is the origin of the species name monilicornis.

They have two compound eyes and three ocelli, or simple eyes. The large compound eyes on the sides of their heads assess their surroundings, focusing on shape and color. The three smaller ocelli (singularly ocellus) are responsible for orientation and navigation. They do not have corbiculae, making them incapable of gathering pollen. Box-headed blood bees also have underdeveloped wax glands, rendering them unable of producing the wax that is a necessary component of brood cells. As parasitic bee species, box-headed blood bees do not have a worker caste

Behavior

Box-headed blood bees are a solitary species of obligate kleptoparasites. These bees do not live in colonies. They utilize the nests of other bee species in which to deposit their eggs in cells that have been prepared for the host bee’s brood. In some cases, Sphecodes monilicornis may usurp occupied nests, laying their own eggs alongside the eggs of the host bee.

Klepto queens may also deposit their eggs on top of the host’s eggs. In this case, the kleptoparasitic larvae will feed off of the host’s eggs and provisions. And there are situations in which the queen box-headed bee will destroy the host’s eggs and/or larvae prior to depositing her eggs in the host’s provisioned brood cells. The species of the host bee and the conditions present in the nest determine the precise behavior. As parasitic bee species, box-headed blood bees do not have a worker caste, only queens ad drones. The drones, all male, do little more than mate with the queens and forage for themselves.

Sphecodes monilicornis has a wide range of host species and can parasitize a variety of bee genera, including Halictus and Lasioglossum. Their principal hosts are the bloomed furrow bee (Lasioglossum albipes), the common furrow bee (Lasioglossum calceatum), the orange-legged furrow bee (Halictus rubicundus), and the sharp-collared furrow bee (Lasioglossum malachurum).

Due to evolutionary adaptations, box-headed blood bees do not have functional wax glands, or corbiculae (pollen baskets). These adaptations leave the species incapable of building nests and provisioning brood cells. Because these bees are unable to care for their offspring they are considered obligate kleptoparasites. The species depends on its host species for its very survival.

Box-Headed Blood Bee: Habitat

Sphecodes monilicornis tend to live in the preferred habitats or their host species. They and their host species, which consists of several different furrow bees, are commonly found in open habitats such as fields and meadows, as well as in urban and suburban areas, including backyard gardens. The host species are ground nesters, building their nests in loose well-drained soil. They are a solitary species and do not form colonies.

Diet

Box-headed blood bees are generalists foragers and exceptional pollinators. like their host species, box-headed blood bees forage on a vast array of wildflowers, stone fruits, apples, pears, sunflowers, and alfalfa. Sodium is a necessary element in the box-heads diet. Pollen and nectar provide very little, if any, sodium. This is why these bees are attracted to human perspiration and other sweaty creatures. Evolution has favored box-heads with long, slender tongues to more easily lick the perspiration from human skin or animal fur.

Box-Headed Blood Bee: Predators and Threats

Predators

Sphecodes monilicornis predators include birds, lizards, and spiders. Sparrows and flycatchers will eat box-headed blood bees. The Western fence lizard (Sceloporus occidentalis) will eat these bees, too. And spiders, like the goldenrod crab spider (Misumena vatia) will snack on bees that they snarl in their webs. Parasitic wasps, such as cuckoo wasps (Chrysididae), lay their eggs in the nests of Sphecodes monilicornis, and their hosts. The wasp larvae will feed on the bee eggs/larvae.

Threats

Sphecodes monilicornis faces a variety of threats including habitat loss, climate change, agricultural chemicals, and disease. The loss of natural habitats, such as grasslands, meadows, and other open habitats from urban sprawl reduces the availability of suitable nesting sites while increasing competition for food sources. Changing weather patterns and temperatures affect the timing of bee emergence and the blooming of food sources. Toxic chemicals used in farming to increase crop yield have deleterious effects on bee populations. Some of these toxins, like neonicotinoids, cause digestive issues in bees, the effects of which can be widespread.

Conservation Status and Population

The IUCN Red List of Threatened Species lists 11 species of Sphecodes. However, Sphecodes monilicornis is not among them. However, all of the species that are on the list are classified as unknown. This is not an unusual state of affairs for bee populations. thanks to their global spread and the colossal number of species. These two factors result in bee populations not being well-documented. However research is discovering that the populations across all species of bees are declining at an unbelievable rate. It would be logical to deduce that box-headed blood bee numbers are also trending down.

Box-Headed Blood Bee: Lifecycle

The lifecycle of a box-headed blood bee begins when the queen emerges from the host nest in the spring. She has spent the winter pupating in her brood cell, emerging as an adult. She will forage and mate before scouting for an appropriate host nest in which to deposit her eggs.
Once she has chosen a nest, she will revisit it several times prior to entering it to deposit her eggs. Depending on the specific host species, the kleptoparasitic queen may destroy the host’s eggs and larvae. Box-headed blood bees will deposit their eggs in empty brood cells without disturbing the host’s brood cells. Once she has deposited her eggs, she leaves the nest, depending on the host species to nurture her brood. Her brood will overwinter in their pupal casings within the host nest, emerging in the spring to begin lifecycle again.

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