Black hornet - a misleading insect

the essentials in brief

• The big black hornet is a type of bee. It is known as the blue-black, large, or purple wooden bee. The species is unmistakable due to its striking body features, which are reminiscent of a bumblebee.
• As a heat-loving species, the wood bee is mainly found in southern Europe. Your area is increasingly expanding to the north.
• The solitary bees live in dead wood or the earth. They belong to the early flying pollinators and are active until midsummer. Suitable niches are sought out for wintering.
• Wood bees do not specialize in plants. Wisteria are commonly visited woods. The insects are considered harmless.

Who is the black hornet?

Anyone who has seen this insect once will never forget it. With a bumblebee-like body and the striking size between 20 and 28 millimeters, the animal looks almost frightening. In fact, it is the largest native bee species that does not belong to either bumblebees or hornets. It is the blue-black wooden bee with the scientific name Xylocopa violacea.

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Typical and noticeable features:

• blue wings
• blue-black body
• black hair

distribution

The insect has many names such as blue, purple or large wooden bee. The species is native to southern and central Europe. Until the 1980s, the distribution area in Germany extended to the Upper Rhine Plain. Since 2003 the wood bee has been spreading increasingly northwards. Today it can be seen as far as Schleswig-Holstein and partly in southern Sweden.

Frequency in Germany

While the wooden bee was classified as endangered in the 1980s, the population has since recovered. By giving up orchards, nature was able to develop independently, so that more dead wood emerged. At the same time, the heat-loving species is favored by rising temperatures, so that it can spread to the north. However, suitable nesting sites are also in short supply in warmer areas of Germany, so that wooden bees rarely appear there.

The wooden bee lives here:

• on orchards with dead trees
• at structurally rich forest edges
• in natural gardens and parks

Are there several types?

In the warmer regions within the German-speaking area you can observe three species of wood bees between April and August. They are difficult to distinguish based on their physical characteristics. With a length of 15 to 18 millimeters, the small wooden bee is smaller than its relatives. The blue-black wooden bee is usually between 20 and 25 millimeters in size, while the eastern wooden bee reaches a body length of 22 to 28 millimeters.

	German	distribution	Nesting place
Xylocopa violacea	Big wooden bee	Austria, Switzerland, Germany	rotten dead wood and thicker stems
Xylocopa valga	Eastern wooden bee	Austria, Switzerland, Germany	rotten deadwood
Xylocopa iris	Little wooden bee	Austria Switzerland; lost in Germany	medullary stems, diameter: 11-16 mm

Way of life and development

Wood bees in Central Europe live solitary. They dig their tunnels themselves in crumbling dead wood or plant stems containing marrow, as the insects use their powerful upper jaws. Depending on the thickness of the tissue, wooden bees gnaw a passage or a complete system of several parallel tunnels that branch off from a main passage. While the nest entrance remains open, wooden bees close the brood cells in their nesting passages with a substance made from wood or plant pulp particles and saliva. They are lined with a waterproof substance so that the brood is optimally protected.

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development

When the warm rays of the sun herald spring, wooden bees wake up from their hibernation and go looking for a partner. It takes no more than two months for the egg to develop into an adult wooden bee. The insects produce one generation per year. Females live unusually long for bees, so they get to know their offspring themselves. This ability to survive is known from furrow and mace horn bees.

The impressive Brummer like sunlit habitats with a large variety of flowers and thick dead wood.

This is how wood bees overwinter

Before wooden bees go into hibernation, they explore their surroundings for the rest of the year. For the hibernation they withdraw into their birth nests or look for other hiding places. Their wintering strategy differs from the concept hornets follow:

	Wooden bee	hornet
Who hibernates?	both genders	mated young queens
What is needed?	mostly above ground, protected crevices	low-light, rain-protected cavities
Where is wintering?	Wall crevices, holes in the ground, own nests	Hollow trees, attics, bird nest boxes, deadwood
How do you overwinter?	individually or in small groups	individually, rarely in small groups

What do wood bees feed on?

Wood bees feed on pollen and nectar from various plants. Early flowering species are of great importance, as the insects are already busy building their nests from April. In the crop and with the help of the hind legs, they transport the pollen into their nests to feed the brood. Your food spectrum is broad and should persist into midsummer:

Wood bees prefer large-flowered plants:

• Mint : winter jasmine, sage, ziest
• Aster family : meadow knapweed, thistles
• Predator plants : Adderhead
• Butterflies : Chinese and Japanese wisteria, flat peas

Tips

Wooden bees are considered to be loyal to their location and keep returning to their old breeding grounds. Therefore, you should not make any intensive changes in your garden.

Digression

Intelligent beings?

When the flowers are large enough, the wooden bees use the normal entry port via the flower opening. They graze the flower organs and act as pollinators. Most of the pollen is transported with your goiter. Occasionally the insects use a different method of obtaining food.

As so-called nectar robbers, wood bees use their powerful mouthparts to gnaw through the flower tube. In this way they get the coveted nectar of deep flowers, which their long tongue is denied in the normal way. In this form, the insects get hold of food without doing the polling in return.

Toxic and dangerous?

The wooden bee has a sting that it can use to inject its venom into a potential attacker. This happens extremely rarely because the species does not behave aggressively. A sting is only to be feared if you crush or otherwise threaten the insect.

Tips

If you collect wild herbs for your own use, you should leave the bouquets in the fresh air for a while before washing and then shake them well. This way, hidden guests can get away and avoid a sting.

frequently asked Questions

How can I help the black hornet?

Wood bees depend on dead wood, which is rare in tidy gardens or forests as well as in fields. Well-intentioned clean-up work destroys the wood bee's valuable habitat. Leave the trunks of dead trees standing or create a pile of thick trunks to provide a retreat for the impressive species. With a diverse range of basket, butterflies and mint plants, you offer the insect important food.

Design tips:

• Place rotten stumps on a stone slab when the soil is wet
• Lay out dead tree trunks on dry sandy soil
• Tie dead branches to trees at an angle
• Combine early bloomers and summer bloomers

A strange black hornet that is about two centimeters tall has settled in our half-timbered house. Like a wood worm, it drills thick holes in the beams so that sawdust falls out. What can we do against it?

Wooden bees do not stop in front of half-timbered houses if the wood has become brittle as a result of the natural aging process. If your building has been settled, this is an indicator of aging. It is an ideal nesting place. To prevent such an “infestation”, you should protect the wood from weathering. Treat it with glazes (€ 59.87 on Amazon *) and varnishes to deter the wooden bees. Avoid injuries in the wood from saw cuts or nail holes. Such cavities are often populated.

Stop already started colonization:

1. Place fruit tree stumps or old pieces of joists nearby
2. Drill holes as an incentive for new settlement
3. Cover entry holes in the framework

What kind of black giant hornets are they that appear in Turkey or Croatia?

There are different species of the hornet genus, which can reach impressive dimensions. The Asian hornet (Vespula mandarinia) caused a particular stir. The species reaches dimensions between 27 and 55 millimeters and is characterized by a predominantly black abdomen with a wide yellow band. However, supposed sightings of this giant hornet in Europe are confusing with other species, as this insect is found in East and Southeast Asia:

• Oriental hornet (Vespula orientalis) lives in Southeast Europe, e.g. Turkey
• Vespa velutina (colloquially: Asian hornet) was introduced to Europe

How do wooden bees collect their nectar?

Females collect pollen mainly in their crop but also with their hind legs. It crawls into the nest up to the brood cell and turns to face the entrance. By cleaning the back legs, the pollen is removed. The female solidifies the particles on the ground using the head and mouthparts for assistance. Sometimes it rotates several times before all of the pollen is cleaned off and piled up.

How do wood bees process the collected nectar?

The females mix the pollen with honey in particles to make a paste. This is deposited in a separate corridor that is parallel to the nest entrance. The color of the paste differs depending on the nectar collected. It varies between brown, dark red, dark green and beige.