Identify wild bees: Profile and photos of the trouser bee
by Michael Watson (comments: 0
In the brown-rumped trouser bee, the females wear the pants - in the truest sense of the word! The females of Dasypoda hirtipes have bushy hairs on their legs that look like baggy pants. With these "pants", the wild bee mothers can transport pollen super efficiently to provide their offspring with food. Unfortunately, these beautiful bees are no longer to be found everywhere in Germany: in many regions they are considered endangered.
| Name | Brown-rumped trouser bee (Dasypoda hirtipes) |
| Size | 12-15 mm |
| Flight time | Mid-June to the end of September |
| Occurrence | Regionally endangered |
| Flower preference | Specialized in composite plants (e.g. bittercress, chicory, pigweed) |
| Habitat | Sand pits |
| Nesting method | Self-dug cavities in the sand |
Trouser bee: Where do trouser bees nest and which wildflowers do they like?
The brown-bristled trouser bee is a pollen specialist and is very selective when choosing a nesting site. As its habitat is being decimated by humans in many places, this wild bee is on the Red List of endangered species. However, there are regional differences here: In Baden-Württemberg, Bavaria and Thuringia, the breeches bee is endangered; in Hesse, North Rhine-Westphalia and Saxony-Anhalt it is on the so-called "early warning list" and in the rest of Germany it is (still) common.
When choosing a nesting site, the females of the brown-bristled trouser bee dig holes in the sandy soil, which can be up to 60 centimetres deep. Branching off from the main tunnel, the female then digs further side tunnels, each of which becomes a brood cell. As the females have to look after so many offspring, it is convenient that a lot of pollen gets caught in their legs. She strips this off into her brood cells to provide her offspring with enough food for the winter. However, foraging is not always so easy for the trouser bee, as it is oligolectic. This means that it only flies to the flowers of a particular plant family - in the case of the brown-bristled trouser bee, these are the composite flowers such as chicory, bittercress, sow thistle, piglet weed, hawkweed and so on.
Hosenbiene erkennen: Äußere Merkmale und Bestimmungshilfe
The brown-rumped trouser bee is fairly easy to identify as the females wear their distinctive "pants" on the third pair of legs. If the trouser bee has been busy and has visited many flowers, these pants become full of pollen and appear even larger. It almost looks as if the trouser bee is wearing baggy pants! The females of the trouser bee grow to around 15 millimetres, the males are somewhat smaller and do not grow larger than 14 millimetres.
The thorax of the breeches bee is black with thin white marginal bands. Its head and thoracic segment are, like the legs, very hairy. To distinguish Dasypoda hirtipes from other species of trouser bee (such as the rough-footed trouser bee or the dark-fringed trouser bee), you must observe the wild bee while it is feeding. If it flies to composite plants such as chicory, then it is most likely a brown-bristled trouser bee.