Wood boring beetles i.d.

[ricwine]

I recently dug up an old tree stump in the middle of my lawn. The wood was so rotten i could pulp it with a shovel. I found it riddled with cockchafer larvae. Also some black beetles. They were black and about an inch long or a bit bigger. With mandibles/pincers ? on both sides of there head rather like car windscreen wipers over a windscreen. When they were out of the wood they were sluggish and only one walked off.

I see these beetles in my garden over the summer. And dont think anything of them. Were the beetles going to emerge this year after changing from Pupae. Or were they trapped and unlikely to ever emerge, as daft as that sounds. If they were close to the wood suface then fine. Or they would have had to turn around and get through a lot of chewing.

Sorry no pics but i will try to find the species.

richard

Peterborough, cambs

[jaguarondi]

Maybe they were (lesser) stag beetles and their larvae - the larvae are similar to cockchafer larvae

[ricwine]

Hi Jag

Thanks for the reply. It is not the lesser stag beetle. After over an hour checking the web for British Beetles, Wood land Beetle and Wood boring Beetles with no luck. I will try looking for beetle larvae and hoping it shows a pic of the adult beetle stage. A bit stumped as I thought the answer would be relatively easy to obtain. The cockchafer larva i did look up on the internet. And they seemed to match exactley. I put about 8 of those big larvae onto my bird table. Which gave a Robin and a Blackbird a gourmet meal. The tits ignored them though.

The lesser stag does have 'windscreen wiper' antlers. These beetles are straight and a lot longer. They are also inverted accross the beetles face

right to left
left to right

Think of a bull bar on a car. So im none the wiser. But I am sure that I have seen these beetles before.

[Matt Smith]

I'm still thinking that the larvae you had in the stump will be Lesser Stag larvae rather than Cockchafers. Cockchafer larvae feed on the roots of grasses so are unlikely to be found in a rotting stump. Lesser Stag larvae do feed on decaying wood.

I'm still trying to visualise what you mean by "windscreen wiper" antennae. If you could post up a picture of something similar if you can find one then perhaps we can start heading off in the right direction.

Your beetles could be one of the larger Carabids or Ground Beetles, these do overwinter in dead wood and do have long antennae and large jaws. Try looking up "Violet Ground Beetle" - are we getting warmer?

[ricwine]

The beetles ( 3 or 4 ) were big and kinda squat looking. The violet ground beelte that you suggested was not these kind. You get the feelers/antenna are straight accross the head on the lower side. They were headfirst in the wood in chambers. which made me wonder how they were going to get out?.

we will crack the case, and thanks for your replies

richard

[ricwine]

ok a possible is plate jaw beetle of some type. but i will investigate that further. there antenna might 'logically' be tucked inwards if they are in a small hole. but i have seen this with the beetles outside and active as well.

keep smiling

richard

[ricwine]

this gives you a fair idea. big oversized pincers really

plate jaw beetles ??

[Matt Smith]

Plate-jawed beetles is not a term I had heard before, a quick Google showed the term being used for some of the smaller Carabid / Ground-beetle species.

The "feeler" on the lower head are the palps, part of the mouthparts, the antennae will be tucked away somewhere, so you may not see them.

As for what they were doing, they were either in their pupal cells or hibernating. If they got in they can get out, even if they have to reverse back out of the crevice they got in.

[ricwine]

They are still not identified. And i have my fingers crossed that i will see them over the summer. So i have just ordered a couple of beetle reference books from the library. Hope that we get a result there.

Thanks Rich