Carabus ullrichii is central-european carabus species, which inhabits a very broad variety of habitats, from dry to wet, and from open cultivated land to large forested areas. It only avoids dense and dark forests. Despite this eurytopic character the species is often uncommon, quite localised and difficult to find. It may occur in a tiny part of a large forest where it can be locally abundant, to quickly decrease in numbers in the adjacent forest habitat and be absent in most of the other forest parts. Which is quite contradictory to the fact that it can theoretically occupy a very broad range. Probably the local populations demand specific microclimatic and abiotic characteristics, especially during their larval stage, of which so far we don't know enough to explain the species' local absence or occurrence. Moreover the species can be very abundant in some place during one year, whilst the species seems to survive almost unnoticed during the next years. Local entomologists told me about this phenomenon around Budpest, where the species is in some years seen very frequently, even walking during daytime in the middle of villages around Budapest and in other years it' s a tough species to find. With all this knowledge in advance I was very uncertain of finding the species, and thus I was very happy that some keen Hungarian entomologists helped me to find the species.
The species also shows some striking colour variations in the southern subspecies 'fastuosus' and 'arrogans'. The specimens found around Budapest are belonging to the subspecies 'ullrichi' (Turin & Al.) or to 'kolari', according to Rautenstrauch, who distinguishes the Hungarian population as a separate subspecies.
Most of the populations of this species seem to have suffered very severe declines during the past decades, probably mainly due to habitat loss and the intensification of the agricultural practices.