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14 messages
02/07/2012 at 12:03

I have a small pond containing several larvae of the Great Diving Beetle. I have read that this is quite a vicious predator.I also have newts in the pond. Will this beetle attack them and should I therefore remove the larvae and relocate them elsewhere?

02/07/2012 at 14:55

Absolutely.  Relocate them as far away from your pond as possible.  They will even eat small fish once fully grown.  Now, I'm not saying you are wrong - I would not presume such a thing - but could they be dragonfly larvae?  They are quite similar - bulging eyes and minus the claws on the front.  Here are a couple of photos.  Beetle first and then dragonfly.  The dragonfly larvae can stay in the pond for a couple of years before crawling up a plant stem and turning into the most magnificent creature.  A joy to watch.


02/07/2012 at 18:46

Ive had experience of these beetles amazing things but yes get rid of them and good luck they come to the surface so briefly to breath then dive again it will drive you crazy have a fishing net on a long pole for the job. As an adult they can fly!! That second photo doesnt look like the adult great diving water beetle we had maybe male and female different

02/07/2012 at 19:25

No, the second photo is the dragonfly larvae.  I probably didn't make it clear when I said "beetle first and then dragonfly", meaning the order of the photos.  Both are difficult to catch. 

02/07/2012 at 20:50

No just me not taking my time reading as usual makes perfect sense oops

03/07/2012 at 07:12

I'm sorry but I think you're crazy - why would you remove them?  They're amazing, and anyway, it's all part of the balance of nature - they will eat some of the pond inhabitants, so will the newts, they all prey on each other - big fish eat little fish etc.  Presumably the pond's been there a while and its bio-diversity has been established all on its own?  When they pupate they will fly away.  Later more adults will come and lay their eggs and so the cycle begins again.  If they didn't all eat each other the pond would be stuffed full.  

Human beings always want to interfere and control, thinking they know best - but Nature has been a long time developing the system 

03/07/2012 at 20:26

Quite agree, Dovefromabove, but Jeanne has a small pond and if she wants anything to thrive then there has to be some intervention.  It's ok to let nature take its course when there's space for it to do so, but who wants a small pond full of nothing?   Hubs and I have had ponds for years - big ones, small ones, natural ones and specialist ones and one thing is certain, if you let one thing dominate you'll end up with an uninteresting pond.

I'm sure you wouldn't let natural plants (weeds) do their thing in your flower beds without intervention.  Just because they don't get up and swim or crawl about doesn't make them less of a pest.


03/07/2012 at 21:12

But my point is that if the newts and other pond residents are not predated they may become overcrowded and unhealthy - or should they be culled? 

04/07/2012 at 09:03

Dragonfly nymphs are also voracious predators, by the way.

04/07/2012 at 10:23
FloBear wrote (see)

Dragonfly nymphs are also voracious predators, by the way.

And so are everything else.  Fish will eat their young and we once put 40 koi fry in a seperate tank together and a few hours later there was just one fry left - which was fatter.  So I guess it's up to Jeanne F to decide what should stay and what should go.

04/07/2012 at 11:16

The great diving beetle larvae isnt called the " water tiger" for nothing. Great Diving Beetle larvae will eat anything they can catch and are said to be even more vicious than the adults. Their favourite prey includes tadpoles and any other insects such as water boatman ( another active predator) within reach. They are also cannibalistic and will eat other Great Diving Beetle larvae. Large larvae in the final stage before pupation, are of sufficient size to even catch and eat small fish.

The larvae are larger than the adult the larvae are around 50mm in length the adults being around 30mm.

As with all things in nature it is a balancing act , the larvea may eat tadpoles etc but being large birds esp thrushes and blackbirds seem to be keen on them ( in my garden anyway) along with frogs, toads and newts , maybe revenge for eating their babies ? . With kingfishers, water and wading birds as well as fish taking them in the wider countryside. The  beetles pupate in areas of grass or soil near the pond so i imagine animals use the pupae as a nice little snack as well !

I should imagine that a natural balance will be achieved in the pond as even a large pond can only support so many diving beetles and dragon flies !

06/07/2012 at 11:21

Many thanks Robot, especially for your superb photos. As you suggested, I can see now that they are actually dragonfly larvae so I shall leave them in peace and await developments. It is great to see so many responses offering good advice, I know where to come next time I have a problem. Many thanks to all who replied

09/07/2012 at 10:31

No problem.  I hope you can catch the day when the dragonfly emerges.  It takes some time so there'll be time to grab the camera.  When our children were young they would often be late for school as they would spot a larvae emerging early in the morning and we would all sit around the pond and watch it - ignoring the school bus.  Happy days.

23/07/2014 at 07:57

What a very enjoyable forum. Best pictures of dragonfly and diving beetle larvae that I have seen, We have a new pond (approx 6 weeks) and we had a lot of diving beetle larvae up until two days ago. They now seem to have all gone though I found a dead one floating on the surface this morning, What do you reckon may have happened to them?


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