Agabus sturmii (Gyllenhal in Schönherr, 1808)

This species is generally common from lowland to low mountain altitudes throughout central and northern Europe, from Spain and France through northern Italy to Asia Minor and north to the UK and central Fennoscandia, further east it extends through northern Russia to Siberia. Here it is common and often abundant throughout the UK including all the islands with the exception of Shetland and is, along with A. bipustulatus (Linnaeus, 1767), our most common member of the genus. Adults occur year-round, generally in small and well-vegetated water bodies but also occasionally in slow-flowing drains in marshy areas, they have been recorded from a wide range of habitats including peaty and brackish-water ponds but may be absent in limestone and chalk districts in southwest and central of England, in general they might be expected from any small and permanent body of water e.g. we have recorded them in numbers from cattle troughs and weed-choked garden ponds. They overwinter among marginal substrate or under debris and become active in April or May, at which time they may be abundant alongside other common dytiscids such as Colymbetes, Ilybius ater, I. fuliginosus or Agabus bipustulatus. Adults are fully-winged and capable of flight but are rarely recorded at light or in flight-interception traps; they breed in the spring and oviposit in stems or among roots of submerged vegetation. Larvae develop through the summer and are fully-grown by July or August, they pupate among marginal substrate and new-generation adults appear from July to September, these are active until late in the autumn when they will leave the water to overwinter; so far as is known this species does not overwinter in the larval stage. Both adults and larvae are predatory, feeding on small invertebrates and the early stages of other insects, and adults will readily consume carrion.