What is this small insect with a rounded brown head burrowing into my rhododendron?

Question

I caught this bug burrowing into the trunk of my rhododendron, and I persuaded it to exit its home.

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Here's a close up of said worm.

I can't imagine it being other than damaging to my tree. Anyone know what it is? The location is Wellington, New Zealand.

Edit: the bark had been damaged by my plastic rubbish bin rubbing against it and I believe this is why some beetle laid its egg here. I removed the frass before taking the picture, and I admit I did use a Philips screwdriver to encourage the woodworm to leave its new home in my tree. The hole is about 4 mm (.15 in) in diameter so I think it's too big for a rhododendron borer which I'm not even sure we have in NZ. The holes of the two tooth borer are said to be oval but this one seems quite round.

Hi Graham! I know nothing about these things, but spent an hour searching the internet, and I can't figure it out! (You've probably already done that!) I agree that it doesn't seem to be a rhododendron borer. Do you have any June bugs or similar beetles? Some of their larvae have rounder heads with spiky fur, and similar bodies, like the [stag beetle](http://www.pbase.com/lejun/image/153759805), although I don't think that's it! Some wood borers are common to azalea and rhododendron. [This NZ site](https://www.rhododendron.org.nz/) is worth a look. Sorry I couldn't help you! — Sue Saddest Farewell TGO GL, Jan 29 '18 at 22:05

score 2 · Answer 1 · answered Jan 20 '18 at 17:58

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A borer, don't know the specific one. Almost any plant can be attacked . They are difficult to kill with poison ( Lindane). It is usually more practical to kill them with something like a wire; normally only one or a few.

answered Jan 20 '18 at 17:58

blacksmith37

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Don't borers eat dead wood? – Graham Chiu Jan 20 '18 at 19:57
I have seen them in live trees - oaks, pines, birch, etc. – blacksmith37 Jan 23 '18 at 00:49

score 0 · Answer 2 · answered Jan 22 '18 at 20:40

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Looks like something we have here, a Leopard Moth (Zeuzera pyrina) however the location information I have is quite wrong and I've never seen anything like this before munching into a Rhodo? the best thing is to prune out the affected wood and burn it. keep an eye out for anymore- just try to keep the site clean and remove any dead material around the parent plant. I wouldn't bother spraying for one occurrence.

answered Jan 22 '18 at 20:40

olantigh

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But not found in New Zealand so it's probably something else. – Graham Chiu Jan 22 '18 at 22:47

What is this small insect with a rounded brown head burrowing into my rhododendron?

2 Answers2