Bombus (Thoracobombus) humilis
Bombus humilis is a widely spread species.
West, it is found in England and Wales (ssp. anglicus) but neither in Ireland nor Scotland and in the Iberian peninsula, north of the 39th parallel (sspp. paraurantiacus and quasimuscorum) but not in Portugal.
In Fennoscandia B. humilis halsahlianus is present up to the 62nd parallel, with some more northern locations in Sweden, along the Gulf of Bothnia. In Russia, the northern limit of B. humilis subbaicalensis lies about the 60th parallel. In Italy, it extends southwards to Calabria (39th parallel) (ssp. propeaurantiacus) and in Greece, to central Peloponnisos (about 38th parallel) (forms aurantiacus and tristis). The ssp. insipidus extends in Turkey to the Hakkari region and down to the 36th parallel in the Iranian Mazandaran. It is common in the Caucasus. B. humilis is absent from all the major Mediterranean islands and from N. Africa. It is very uncommon to absent on the Mediterranean littoral. In some regions, the coat of B. humilis is quite constant, e.g. in central and western France (ssp. quasimuscorum), in the United Kingdom (ssp. anglicus) and in the Caucasus region (ssp. insipidus). In other places, the variability is much higher, with three to four coexisting forms. This is the case in Belgium and the Netherlands, in most of central and east Europe, in the Balkan and in W. Anatolia.
The local population densities are also variable. The distribution of the species is patchy : as for B. ruderarius and B. sylvarum, the species may be quite common in one place and absent from its surroundings.