Wool Carder Bee

Anthidium manicatum, commonly called the European wool carder bee or simply wool carder bee, is a fascinating and distinctive species of solitary bee native to Europe, Northern Africa, and Western Asia. The wool carder bee has been introduced to other parts of the world, including North America, where it is considered a pest species. This species is known for its striking appearance, with black and yellow markings on its abdomen, and its intriguing behavior of collecting and carding plant hairs to construct its nest. Anthidium manicatum is the most widely distributed and unmanaged bee on the planet! Keep reading to learn more about these captivating bees.

Five Fuzzy Facts about Wool Carder Bees

• Wool carder bees are a species of solitary bees native to Europe
• These bees get their name from their behavior of collecting and carding (cleaning and aligning) fibers from plant leaves, such as lamb’s ear, to use as nesting material.
• Male wool carder bees are territorial and defend their patch of flowers, aggressively chasing away other insects, including other wool carder bees. They will even grapple with other males in mid-air!
• Wool carder bees have smooth stingers and can sting repeatedly. However, they are not typically aggressive towards humans and will only sting if they feel threatened.
• Wool carder bees are important pollinators of a variety of plants, including many garden flowers. They are particularly attracted to plants in the mint family, such as catmint and bee balm, as well as other tubular-shaped flowers

Scientific Name

The binomial scientific name Anthidium manicatum translates as anti-sleeves or sleeveless. It’s not abundantly evident why Carl Linnaeus (1707-1778) would have christened this species as such, but we must assume he had his reasons. The common name, wool carder bee, refers to the behavior of females of the species who use their mandibles to scrape hairs (trichomes) off of the stems and leaves of plants to construct their nests. Trichome means hair in Greek. Trichomes protect plants from an array of threats. Carding wool is a process of preparing raw wool fibers for spinning into yarn. The process involves using a carding tool, such as a hand card or drum card, to separate and straighten the fibers. The carding tool has small wire teeth that catch and align the wool fibers, very similar to the wool carder bee’s mandibles.

Wool Carder Bee: Appearance

The wool carder bee is a small-to-medium-sized bee. Wool carder bees are about 0.4 – 0.7 inches (11-17 mm) long with wingspans of approximately 0.75 inches (20mm). Their compact body is relatively free of setae (hairs) which gives them a wasp-like appearance. Their wings are transparent with brownish veins, and their legs are yellow with black markings. Females have mandibles that are long and curved, which they use to collect plant fibers for nest building. The abdomen of Anthidium manicatum is black with yellow markings that vary in individuals.

Wool Carder Bee: Behavior

Anthidium manicatum is a solitary bee species. They do not live in colonies. They are active during the day and are known for their fast and darting flight pattern. Male bees are territorial and will defend a patch of flowers or a nest site, aggressively chasing away other insects that come too close. Females collect plant hairs and pollen, and they can often be seen visiting a variety of flowers in search of resources for their nests. Female wool carder bees have smooth stingers and can sting repeatedly. However, they are not typically aggressive towards humans and will only sting if they are threatened or handled.

Resource Defense Polygyny

Though female wool carder bees are benign, males of the species are highly aggressive. Especially when it comes to mating. Male wool carder bees practice resource defense polygyny.
Resource defense polygyny involves the males of the species controlling access to resources that are attractive to potential mates. By controlling access to these resources, such as food, nesting sites, or breeding territories, the male can attract multiple females and increase his reproductive success. They establish territories around flower patches and aggressively chase away other males. By doing so, they can monopolize access to the flowers and the females that visit them, increasing their mating opportunities. The males also mark the flowers with a pheromone to attract females and deter other males. Males, however, do not have stingers, making them essentially harmless to humans.

Wool Carder Bee: Habitat

Anthidium manicatum is the most widely distributed and unmanaged bee on the planet. These bees can be found in a variety of habitats, including meadows, gardens, orchards, and open woodlands. These bees prefer open areas with plenty of flowers and nesting sites. wool carder bees are native to Europe, Africa, and parts of Asia, but have been introduced to other parts of the world, including North and South America, Australia, and New Zealand.

In these introduced areas, the bees are considered invasive species and can sometimes out-compete or displace native bee species. Within their native range, wool carder bees are found in warm, sunny habitats such as open meadows, fields, and forest edges, where they can find abundant flowers for nectar and pollen and suitable nesting materials. They are known to prefer open areas with sandy or rocky soils, which provide good drainage and a suitable substrate for nest construction. In areas where the bees have been introduced, they may be found in a variety of habitats, including urban and suburban areas.

Diet

Wool carder bees collect pollen and nectar from a variety of plant species, including members of the Asteraceae (daisy) and Lamiaceae (mint) families. However, what makes this species unique is that females also collect plant hairs, which they use to line and partition their nests. They prefer plants with soft, fuzzy leaves, such as lamb’s ear (Stachys byzantina) and mullein (Verbascum thapsus), but will also collect from other fuzzy-leaved plants like sage (Salvia officinalis) and lavender (Lavandula spica)

Wool Carder Bee: Predators and Threats

Predators

Wool carder bees face a variety of predators. The eggs and larvae are vulnerable to predation by parasitic wasps and flies, which lay their eggs on or in the nests. The parasitoid larvae will then feed on the developing bee larvae, ultimately killing them. Anthidium manicatum also serves as a host to several species of parasitic bees. Similar to the wasps and flies, the wool carder bee larvae generally don’t survive. Adult bees may be preyed upon by birds, spiders, and small mammals. They are also vulnerable to a variety of bee-specific parasites, such as Varroa mites, which can weaken or kill them.

Threats

Anthidium manicatum faces a number of threats. A major threat is habitat loss and degradation, as these bees require open areas with abundant flowers and suitable nesting sites. Such sites are reduced by land use changes such as urbanization. The use of pesticides and herbicides also harms the bees, both by directly poisoning them and by reducing the availability of suitable forage plants.
Climate change also poses a threat to wool carder bees, as it alters the timing of flowering and nesting, as well as exposing the bees to extreme weather events and changes in habitat availability.

Conservation Status and Population

The wool carder bee is listed as species of least concern on the IUCN Red List of Threatened Species. The last time these bees were evaluated was in 2013. As the most widespread bee in the world, it is unlikely that its status has changed in the intervening years. However, research is finding that across most species, bee populations are declining at a concerning pace, so it is likely that their numbers are declining. Bee populations fluctuate naturally due to environmental factors and are not sufficiently monitored to produce meaningful statistics.

Wool Carder Bee: Lifecycle

The lifecycle of Anthidium manicatum begins when females emerge from their nests in the spring. after mating, females collect pollen, nectar, and plant hairs to construct their nests in pre-existing cavities. They deposit an individual egg atop a ball of pollen, sealing each brood cell with particulate material, like sand. Each egg is separated by a partition made of plant hairs.
The larvae hatch in approximately 3 days and feed on the pollen and nectar stores. After growing and molting, the larvae spin a cocoon around themselves. They pupate inside their cocoons, and emerge as adult bees, having gone through a complete metamorphosis. The newly emerged adult females will repeat the cycle by collecting resources and constructing their own nests. Wool carder bees often produce two generations within a season. Some wool carder bees overwinter in their nests as adults, while others remain in their pupal form. The entire lifecycle of Anthidium manicatum takes from a matter of weeks to one year.