Alder black beetle rapid spread(Agelastica alni)

[Mr Oz]

I have noticed in the past 12 month or so i have seen increasing number of infestation on especially on alders.

I work in and around Chorley/Bolton/Manchester area. I wondered if it is effecting other parts of the country and if any of you guys noticed the increase.

I

[Khriss]

I shall keep an eye out -  not seen yet but thought SE would have emergence sooner?  K

[timbernut]

I’ve found them recently, but only one or two in close proximity, didn’t know what they were so looked them up, seems they are native, are/can they be a problem?

[Mr Oz]

I havent looked into too deep and from my understanding on whats on google they dont kill the tree. However it causes significant damage to leaves and surely that will have an impact on trees overall health.!

[ABtrees]

Hi Oz

I believe these are Alder Leaf beetles.  I posted some on David's Iggly thread in Feb 19.  We have loads of them in France and something is killing the Alders locally (but I don't think it's these - more the green boring larvae (same thread) that I have yet to identify - help?).  Clearly however if the beetle eat lots of the leaves, the tree is less able to defend itself (we also had a very dry summer last year - so what is the primary issue I wonder). 

 

Anyhow, here is the RHS link

Alder leaf beetle / RHS Gardening

WWW.RHS.ORG.UK

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The metallic blue alder leaf beetle (<em>Agelastica alni</em>) feeds on the leaves of alder trees. It has recently become...

 which suggests control on big trees is impossible.  I note on the web there have been some older (haha) studies into bacterial control (Pseudomonas) but I'm not sure if there is a commercial aspect to this (they apparently also eat Hazel).

[Michael h]

Hi Mr Oz

Looks like your based in the hotspot for the revival of this formally extinct species. seems to have spread quite far in 15 years. not seen it in north east yet but i'll keep an eye out now.

there would appear to be a correlation between Alder leaf beetle and Grey alder (it's preferred diet) in the north west, i wonder if that has helped to it's revival. Although it appears to be on common Alder in your case and this doesn't account for the cluster in the south, maybe that's from the ports?

Where are you timbernut?

cheers

Mike

 

Edited May 25, 2020 by Michael h

[Baldbloke]

I did about 15 years as a fishing ghillie on a river in Tayside. Alder is the most common riverside tree. We had a very similar and very common beetle there. However, it was the colour of a Scarab beetle. More translucent green than black. Regional variation?

[Gardener Joe]

Hi 

Work in area North of Preston ... Saw these on alder in one of my customer's copice last week....

[timbernut]

Hi Mr Oz
Looks like your based in the hotspot for the revival of this formally extinct species. seems to have spread quite far in 15 years. not seen it in north east yet but i'll keep an eye out now.
there would appear to be a correlation between Alder leaf beetle and Grey alder (it's preferred diet) in the north west, i wonder if that has helped to it's revival. Although it appears to be on common Alder in your case and this doesn't account for the cluster in the south, maybe that's from the ports?
Where are you timbernut?
cheers
Mike
 

Hi Mike, sorry only just saw your post, I’m in Norfolk