This is the most common and widespread European member of the family; it is native to the western Palaearctic and the Near East and has a very wide distribution, from Portugal and Spain east through southern and central Europe to Mongolia and China, and from Italy north to southern Scandinavia and the U.K. It is also recorded from Turkey, Syria, Lebanon, Iran and Iraq. Here it is common throughout England and Wales including the Isle of Wight, Anglesey and Man although in the West Country records tend to be mostly near-coastal. Most Scottish records are from the southwest; Dumfries, Galloway and Ayre north to Glasgow, and there is an older record from Fife. The species is well-known from brackish water environments and there are coastal records throughout its range. Adults occur year-round; they overwinter among submerged vegetation and detritus etc. and become active in March or April, they generally inhabit permanent water bodies rich in submerged vegetation and organic detritus, and while they are good swimmers they spend much of their time crawling among vegetation or burrowing through substrate in search of prey. In our south Hertfordshire area they are common in ponds and reservoirs etc throughout but probably more especially so in still water beside reed beds where we have recorded adults in every month of the year. In south Hampshire we have recorded them as abundant in early June around the margins of permanent shallow ponds on heather moorland. Eggs have been found in late spring under decaying Scirpus (Bulrush) leaves, and young larvae have been found in late June. Mature larvae have been recorded in August; they mine among the roots of grasses, sedges and rushes etc. in search of prey, in captivity they have been observed feeding upon dead insects and carrion and these are likely to form a part of their diet in the wild. They obtain air by penetrating roots and stems with the pointed tips of the abdomen and will not swim to the surface to breath unless forced to do so. When fully grown they construct a cocoon low down on a stem or root from secretions and particles of debris etc.  and inflate it with air obtained from the plant, and both cocoons and freshly eclosed adults have been recorded in August. Adults remain active at least until November but in mild conditions may found through the winter.