Acer

I live in the northeast of England.
I have an Acer in a large pot and the stem is covered with a small brown beetles.
It is making the stem black.
I would be very grateful if anyone could tell me what it is, and how to get rid of them.

Dale

 

Can you post a photo?

 

Larger aphids sometimes look like small brown beetles and are common on Acers at this time of year, to the extent they completely cover stems. Agree a picture is needed for a positive ID.

 

Here is the photo of my Acer that you requested.
Thank you for your quick response.
Dale

 

It is scale, possibly Horse Chestnut scale, but didn't realise it had reached that far north yet. (It was unknown in this country not too many years ago). Doesn't do that much damage but is unsightly and possibly slightly weakens the maple.

In practical terms I find the best thing to do is simply to rub the scale off with fingers or a small paintbrush if you prefer. When they start to hatch they look even worse, with white powdery cotton wool stuff showing from under the edges of the scale.

Hope that helps.

Edit: More details on the life cycle of Pulvinaria regalis can be seen at this link: http://www.savethechestnut.com/ChestnutScale.html

 

Thank you.
I have been rubbing them off by hand, but a paintbrush sounds a better idea .
Dale

 

It has been in the Newcastle area for 3 or 4 years at least.

 

Interesting Michael. 40 years to travel 250 miles north from London. I do worry that Japanese maples act as a vector in transporting these pests around the country. Especially as Horse Chestnut Scale are considered an urban pest and seem to be relatively scarce in rural environments.

I saw a couple of anecdotal reports on the internet that in areas of England with heavy infestations of these scale, localised population explosions of Harlequin Ladybirds have been reported, with resultant virtual elimination of the scale in the following year. Obviously such reports have to be taken with a pinch of salt, but maybe it takes an imported Asian predator to deal with an imported Asian pest, as nature intended.

 

It could have been around up here a lot longer than that, that's just the earliest I know of myself. And yes, transport of nursery stock (not necessarily just Acer palmatum) is very likely how it gets around. A single infested delivery could spread it far more than 250 miles in just 2 days.

 

Scaly insect have been around London for more than 10years. They seems to infest not only horse chestnut (conker) but loves the shaded branches of local sycamore (another maple) that lines London streets and park. Also London Plane. Especially bad infestation this time of the year when the sap is rising. On my momiji, they can be effectively got rid of by using a toothbrush and a weak solution of fairy washing up liquid. Keep the first ten down and the infestation recede or stop. My grandmother from the far east taught me that.