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These pages will look at the rarer Water Bugs in Northamptonshire, where they are found, why they are rare and what can or should be done to help improve or monitor the distribution.
The rarity is based on whether it has a rarity status of Nationally scarce, Nationally rare, endangered critically endangered or threatened. There are 9 species Micronecta griseola, Aquarius najas, Aquarius paludum, Microvelia pygmaea, Corixa affinis, Saldula pallipes, Saldula opacula, Saldula orthochila and Salda littoralis.
Micronecta Griseola
Micronecta Griseola
Nationally rare - Found only on the River Nene, Islip.
The most favoured habitat is a slow-moving river with some kind of hard substrate coated with a short ‘lawn’ of filamentous alga. Stray lumps of concrete, concrete bank lining, steel sheet piling, and bridge supports are all worth a look. (Het News Spring 2003)
The main threats for this is that there is only one colony identified in the River Nene. There should be similar habitat to this all the way down the Nene therefore if more extensive searches were undertaken then more colonies could be found. It is likely that this is currently extending its range with climate change.
Photo by: Marko Mutanen, University of Oulu
The most favoured habitat is a slow-moving river with some kind of hard substrate coated with a short ‘lawn’ of filamentous alga. Stray lumps of concrete, concrete bank lining, steel sheet piling, and bridge supports are all worth a look. (Het News Spring 2003)
The main threats for this is that there is only one colony identified in the River Nene. There should be similar habitat to this all the way down the Nene therefore if more extensive searches were undertaken then more colonies could be found. It is likely that this is currently extending its range with climate change.
Photo by: Marko Mutanen, University of Oulu
Aquarius Najas
Aquarius Najas
Nationally scarce - Found only once on the River Welland, Duddington.
This occurs at the margins of lakes and on rivers and large streams requiring flowing water. There are not too many habitats that would suite this in Northants as the River Nene is perhaps a little slow flowing, the River Welland skirts the northern Northants border and the Ouse skirts the Southern board. It has not been found on the River Nene despite searching and not found on the Welland and Ouse in bordering counties however this could still be a lack of recorder effort. It was found once on the River Welland where it just comes inside the Northants border at Doddington.
The main threats for this species is river widening and slowing the flow however this is more a western species that is extending it’s range.
To preserve need to identify and record the colonies on the River Welland in Leicestershire.
This occurs at the margins of lakes and on rivers and large streams requiring flowing water. There are not too many habitats that would suite this in Northants as the River Nene is perhaps a little slow flowing, the River Welland skirts the northern Northants border and the Ouse skirts the Southern board. It has not been found on the River Nene despite searching and not found on the Welland and Ouse in bordering counties however this could still be a lack of recorder effort. It was found once on the River Welland where it just comes inside the Northants border at Doddington.
The main threats for this species is river widening and slowing the flow however this is more a western species that is extending it’s range.
To preserve need to identify and record the colonies on the River Welland in Leicestershire.
Aquarius paludum
Aquarius paludum
Nationally scarce - Found at Wilson’s Pit, Barnwell Country Park, Pitsford Reservoir, Islip Nine arches, Brampton Fisheries, Brackley St James Lake, Rushden Lakes, Stanwick Lakes.
This is a Southern species that is heading Northwards. There are no specific habitat preferences but like Lakes, Rivers and Streams. I have found it mainly on lakes and ponds in Cambs, Beds and Northants and it appears to like overhanging vegetation that it can shelter under and perhaps hunt species blown onto the water. Peter Kirkby has suggested that it replaces A. najas in slow rivers and lakes. It has very healthy populations at now 8 Northamptonshire sites and with the gravel extraction pits recently created and flooded it appears to have plenty of similar habitat to expand into.
The threats would be to open up the gravel pits too much and reduce marginal willows and vegetation. The depth of the water would usually keep these under control without management.
This is a Southern species that is heading Northwards. There are no specific habitat preferences but like Lakes, Rivers and Streams. I have found it mainly on lakes and ponds in Cambs, Beds and Northants and it appears to like overhanging vegetation that it can shelter under and perhaps hunt species blown onto the water. Peter Kirkby has suggested that it replaces A. najas in slow rivers and lakes. It has very healthy populations at now 8 Northamptonshire sites and with the gravel extraction pits recently created and flooded it appears to have plenty of similar habitat to expand into.
The threats would be to open up the gravel pits too much and reduce marginal willows and vegetation. The depth of the water would usually keep these under control without management.
Microvelia pygmaea
Microvelia pygmaea
Nationally scarce - Found in 10 sites.
This is a southern species that is extending Northwards and in the last 5 years from 2018 has expanded from zero to 10 sites in Northamptonshire. It’s habitat is overgrown/dense vegetation and litter at the edges of slow flowing water bodies e.g. ditches, ponds and lakes. It has a healthy population and plenty of similar habitat to expand into.
However uncontrolled scrub invasion from no management, loss of permanent standing water in ditches or pools and over clearance of bankside vegetation will erode habitat. Additionally and pesticide leakage from fields into ditches and pools could affect complete isolated populations.
Controlled management of vegetation to a third each year and surrounding fields to populations should be pasture rather than arable will minimise the effects on current colonies (PK,1992).
This is a southern species that is extending Northwards and in the last 5 years from 2018 has expanded from zero to 10 sites in Northamptonshire. It’s habitat is overgrown/dense vegetation and litter at the edges of slow flowing water bodies e.g. ditches, ponds and lakes. It has a healthy population and plenty of similar habitat to expand into.
However uncontrolled scrub invasion from no management, loss of permanent standing water in ditches or pools and over clearance of bankside vegetation will erode habitat. Additionally and pesticide leakage from fields into ditches and pools could affect complete isolated populations.
Controlled management of vegetation to a third each year and surrounding fields to populations should be pasture rather than arable will minimise the effects on current colonies (PK,1992).
Corixa affinis
Corixa affinis
Nationally scarce - Found at Woodston Ponds and Hampton Harcourt Lake in Peterborough.
It is usually in brackish ditches and pools mostly near the coasts of central and Southern England and Wales. However it is also known from some inland slightly brackish, dykes or ponds on clay. Peterborough was on the coast many years ago and still has some salt deposits and seepages.
With some additional recording this could be found at a few more sights around Peterborough but unlikely to be anywhere else in Northants.
It is usually in brackish ditches and pools mostly near the coasts of central and Southern England and Wales. However it is also known from some inland slightly brackish, dykes or ponds on clay. Peterborough was on the coast many years ago and still has some salt deposits and seepages.
With some additional recording this could be found at a few more sights around Peterborough but unlikely to be anywhere else in Northants.
Saldula pallipes
Saldula pallipes
Nationally scarce - Found in 6 sites.
This is an inland bug that is found in flooded gravel pits , pools and puddles on sandy clays and sandy gravels. Over the recent years with extensive gravel and clay extraction and the building of Reservoirs with extensive drawdown areas, this habitat has increased substansially and this species now getting established is also likely to expand across the county.
This is likely to be under recorded in Northants over the years due to the lack of bug recorders. It is not an easily identifiable species and could have been overlooked.
This is an inland bug that is found in flooded gravel pits , pools and puddles on sandy clays and sandy gravels. Over the recent years with extensive gravel and clay extraction and the building of Reservoirs with extensive drawdown areas, this habitat has increased substansially and this species now getting established is also likely to expand across the county.
This is likely to be under recorded in Northants over the years due to the lack of bug recorders. It is not an easily identifiable species and could have been overlooked.
Saldula opacula
Saldula opacula
Nationally Scarce. Found at Etton-Maxey Nature reserve.
This occurs in estuarine marshes on the east coast, the west coast and a few old records from Scotland. Very little is know about the inland records occurring in the fens around Cambs, Lincs and Northants.
However it appears to be expanding it’s range recently and as the fen habitat expands down the Nene Valley this could expand it’s range further into Northants.
This occurs in estuarine marshes on the east coast, the west coast and a few old records from Scotland. Very little is know about the inland records occurring in the fens around Cambs, Lincs and Northants.
However it appears to be expanding it’s range recently and as the fen habitat expands down the Nene Valley this could expand it’s range further into Northants.
Saldula orthochila
Saldula orthochila
Nationally scarce. Found at Swaddywell Pit Nature Reserve.
Photo by: Rob Ryan
Photo by: Rob Ryan
Salda littoralis
Salda littoralis
Nationally scarce. Found at Etton-Maxey Nature Reserve
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