This is an exceedingly common and widely-distributed bug found. It inhabits lowland slow-flowing rivers, alkaline lakes outside reed-beds and many non- acid, nonsaline ponds and ditches where there is some flow and adjacent sheltering water plants. The bug is a poor colonizer of new habitats although mass flights have been observed and it is taken freely at light-traps.

Overwintered adults oviposit during March-April and development takes a little over two months to give a new generation by late June; a second generation of the year follows to mature around late August and oviposit at that time, and the resulting generation overwinters (S&L, 1959). If the autumn is unduly cold the bugs tend to be somewhat dark although this is the same for many insects.

Distribution:

Found in 65 5km squares and 32 10km squares, this is a very common bug in Northants.

Habitat:

It inhabits lowland slow-flowing rivers, alkaline lakes outside reed-beds and many non- acid, nonsaline ponds and ditches where there is some flow and adjacent sheltering water plants.

Identification:

For the identification of this bug I rely initially on eliminating other species. A blunt ziphus means not a Hesperocorixa sp., no dark patches on palae or tibia and the medium size (c. 7mm) eliminates the larger and smaller corixids.

S.falleni rounded ziphus

S.falleni pronotum with pointed edges

The pronotum has 7 or more pale lines and the edges are distinctly pointed as above (to differentiate from S.dorsalis, S.striata and S.distincta). There is then a difficult separation with three other species that can only be separated by the male palae. Sigara fallenoida is only found in Ireland and also S. longipalis which has not been found in Northants. S.iactans i have just one record for. Therefore at this stage it is safe to assume that you have S,falleni but worth checking all the male palae.

S.falleni male palae