Tiny beetles are decimating city’s elms

TINY HUNGRY BEETLE: Consulting ecologist Ray Mjadwesch checks out the elm leaf beetle which is doing so much damage to Bathurst’­s elms. Photo: CHRIS SEABROOK 030916cbeetle1b

TINY HUNGRY BEETLE: Consulting ecologist Ray Mjadwesch checks out the elm leaf beetle which is doing so much damage to Bathurst’­s elms. Photo: CHRIS SEABROOK 030916cbeetle1b

BATHURST’S elm trees are being decimated by a tiny beetle with an enormous appetite. 

The elm leaf beetle was only found in Australia in 1989, but now the huge elm trees throughout Machattie Park are falling victim to it. 

Consulting ecologist Ray Mjadwesch discovered the beetles in Bathurst a couple of weeks ago, and they had already taken hold in elms across the city. 

He became aware of the problem when he received a call from a friend in Lord Street who wanted to know what was happening to the elm in his backyard.

The leaves were being stripped and the surface of the leaf eaten. 

Mr Mjadwesch found grubs that looked like beetle larvae and brought them back to his office.

After doing some research he realised they were the larvae of the elm leaf beetle. Prior to that he hadn’t even heard of them.

Mr Mjadwesch said now as he wanders around Bathurst just about every elm he sees has been chewed on.

“When you look at how many of the trees in Machattie Park have been affected there must be millions of the little guys in there,” he said.

Bathurst Regional Council’s recreation manager Mark Kimbel yesterday said there had been problems with elm leaf beetles in Bathurst for the past couple of years, however, numbers had now exploded. 

“There is a very heavy infestation throughout the town. It came on very quickly,” he said.

Mr Kimbel said this might have been exacerbated by the hot, dry weather of the past couple of weeks. Beetle activity in all council’s parks and reserves is being monitored.

“We are getting to autumn now so the leaves will start to drop and there won’t be anything to eat so they will soon start burrowing down,” he said.

“If it is a very cold winter that might slow them down. We will start monitoring them again in the spring.”

Mr Kimbel said elms were one of the dominant large tree species in Bathurst. They can be found in parks, streets and in private gardens. 

Some of the elms in Bathurst’s heritage areas would be close to 100 years old. 

“It is concerning. I hope we don’t lose them,” Mr Kimbel said. 

After the elm leaf beetle was discovered in Melbourne in 1989 it spread to Tasmania where it was found in Launceston in late 2002 and Hobart in 2008. It is now well established in these cities.

The Australian Museum found the beetle in Orange about 18 months ago.

Mr Mjadwesch said the beetle was only about one centimetre long. It is light brown with dark edges. 

“It is a small, inconspicuous little beetle, but quite distinctive,” he said.

It is possible to tell an elm has been affected by the skeletonisation of the leaf. The green will have also been chewed off in very large patches. 

Skeletonisation occurs when everything is eaten except for the leaf veins. Skeletonised leaves turn brown and causes them to drop prematurely. 

“The grub eats the leaf and then the beetle eats the leaf, so it will eventually weaken the tree leaving it vulnerable to disease,” Mr Mjadwesch said.

“I don’t know how you would get on top of them. I think we needed to do that when they were first discovered in Melbourne 20 years ago.

“It’s pretty futile to try and contain them now. They will only be back again next year.”

Mr Mjadwesch said some of the really big old elm trees were habitat for possums and other animals because as the elm ages it hollows out. 

He added he has been talking to council about using eucalypts as street trees for many years. 

“If that had happened, the loss of the elms as habitat would have had much less of an impact,” he said. “However, if the elms start disappearing council will have to look at alternatives among the natives.”

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