This is a widespread bug across Northants that is found in still or slowly flowing water in ponds and at lake margins, usually upon clay and associated with thick masses of reeds, Canadian pondweed or other vegetation. It will also include a lot of undissolved organic matter of vegetable and alkaline waters. Sigara distincta or Hesperocorixa sahlbergi are often found in the same habitat.

The bugs overwinter as adults and have a spring and summer generation.

Experiments show that the colour background is perceived through the eyes of the larvae and affects the colour of the insect by acting the rate and amount of deposition of dark pigments in the cuticle: the colour of the adult is dependent upon the background colour of the larval habitat and a local population shows a protective matching to its home waters (SWL, 1959)

Distribution:

This is widely distributed and common across Northants being found in 15 10k squares and 26 5k squares.

Habitat:

Found in still or slowly flowing water in ponds and at lake margins, usually upon clay and associated with thick masses of reeds, Canadian pondweed or other vegetation. It will also include a lot of undissolved organic matter of vegetable and alkaline waters.

Identification:

This is often confused with Hesperocorixa linnei as they both have 6 pale lines on the pronotum however S. fossarum has a more blunt ziphus. There is also a confusion with S.scotti but S.fossarum is slightly larger and darker with a dark mark at the inner angle of the corium and the male palae has a diagonal line of pegs rather than wavy.