Beetle for ID please

[pressld2]

This chap arrived on the sheet at the moth trapping event at Crossness Nature Reserve last Friday...



Any ideas?

Dave P.

[Paul mabbott]

It's a water beetle of some kind - I wouldn't even try to family but perhaps others would ... what size was it?

[JRsbugs]

I had one of these, or should I say my neighbour's pond did and I did a lot of searching for it. The only one that came close was Rhantus frontalis, look at the pic here:

Dytiscidae : ==> www.dytiscidae.org

If those people don't know their Dytiscidae then no-one does.

Janet

[tracker]

Could it be a Great silver beetle UK’s largest water beetle.

[Dogghound]

Its a Rhantus species most likely R.notatus .

[pressld2]

Thanks everyone!

I did consider water beetles but I thought they lived their whole lives in water so dismissed the idea of one turning up on a sheet while moth trapping.

I mean to include a size when first posting but forgot again - d'oh! I would estimate about 15mm, certainly no more than 20.

Rhantus sp. looks very good and while googling for more info I came across a site called russian-insects.com that will sell me a Rhantus - frontalis or notatus - for a mere $2.00. What's that all about?!

Dave P.

[JRsbugs]

These beetles have a strange life cycle, the larva matures very quickly in about three weeks! The beetle I saw climbed to the top of a reed then shot away at high speed. A little over 3 weeks later there was a mature larva in the pond. This site gives an insight into them,

Rhantus suturalis

Tha larva,

Rhantus suturalis - larva (microcosmos.nl)

[pressld2]

Thanks Janet - fascinating stuff! Anything that helps keep the mozzies down gets my vote!

Dave P.

[JRsbugs]

Originally Posted by pressld2

Thanks Janet - fascinating stuff! Anything that helps keep the mozzies down gets my vote!

Dave P.

The larva I saw was carrying off fish food! I guess it ate other things too, with it's qick growth it needed all it could get!