Some solitary bees are as big as honey bees. There are however many much smaller species, most of them are look-a-likes and almost impossible to identify. The Sweat Bees (Lasioglossum) are represented by some 40 species in the Benelux alone. All are quite small. Most Andrena species have a weak stinger and many can not even penetrate the human skin. But even the smallest Lasioglossum species has a strong stinger and their sting is quite painful. Andrena species are solitary bees even despite their sharing a common entrance to a nest sometimes. Among the Lasioglossum species however we find more advanced ways of cooperation. In some species a female might live longer than just one year. Females born in the beginning of the second year may start to help their mother rather than beginning a nest of themselves. There is not much structure in such a cooperation. Other species however have real colonies which are comparible to those of the social wasps. With one species the colony even lives five to six years, because the queen gets that old. The species in the picture is a very rare visitor to our garden so we have seen it merely thrice. Possibly it is not that uncommon but we have been unaware of its presence because of its size. It is the smallest bee we ever had in the garden, about the size of an ant. By the way: it is likely to be Lasioglossum sexstrigatum, but we are not absolutely sure. Sweat Bees are very hard to identify to species level.