Elm Leaf Beetles? Identify and Treat with Tree Technique

How do I know if my tree has Elm Leaf Beetle?

The evidence of your tree being affected by Elm leaf beetle is very easy to ascertain in October to December when new foliage has appeared. At this time the pest is in its first cycle of the season.

Apart from seeing the beetles, the damage inflicted on the tree is quite obvious. Adult elm leaf beetles cause small shot holes in the leaves ranging to 1mm in diameter then lay eggs. Upon hatching the elm leaf beetle larvae then skeletonise the leaf between the leaf veins.

Which species of Elms are vulnerable?

The Elm leaf beetle attacks all species of Elm. The insect feeds on the leaves, causing the leaves to dry up and die. This damage will not usually kill a tree, but it will weaken the tree and make it more susceptible to dieback and attack from other insects and diseases. The Elm leaf beetle can also become a household nuisance by migrating into homes and buildings during the cooler months.

What is the best way to help my tree?

The best way to care for an Elm is to put a management plan in place. This includes treatment during the months of September and October, repeating every 2 years.

Tree Technique has extensive experience, and equipment to treat infected trees. We typically use steam injections, which through the careful use of systemic insecticides, control elm leaf beetle numbers from spreading and in-turn improve the health of your trees.

What are Systemic Insecticides?

Typically, these chemicals are applied to soil and taken up through plants’ roots, or they are applied to foliage or injected into tree trunks.
Systemic pesticides are water-soluble, so they easily move throughout the plant as it absorbs water and transports it through its tissues.

A plant or tree treated with a systemic pesticide no longer becomes a target for chemicals but becomes a participant in making conditions unfavorable to invaders. 

In some cases, a systemic pesticide is safer for the environment than a non-systemic pesticide would be, as less of the chemical ends up drifting onto other plants or contacting non-target insects than if non-systemic chemicals were sprayed.
Call us to discuss your requirements 0498 176 484

What about breeding cycles?

More recently we have seen the Elm leaf beetle successfully achieve three full breeding cycles in the Adelaide Metropolitan area.

Eggs are laid in groups of up to 30 on the underside of leaves. They are pointed, orange-yellow and about 2mm long. The larva is the elm leaf beetle’s most destructive life stage. When full grown, it is about 12mm long and is dull yellow with two black stripes.

The pupa — the stage in which the larva changes to an adult — usually is found around the base of elm trees. The pupae are about 6mm long and bright orange-yellow.
The adult beetle is about 6mm long and yellowish to olive green, with a black stripe along each side of the wing covers. The stripes are sometimes indistinct in the dark olive forms. The adult has black eyes and has four black spots on its thorax.

When the days warm up in the spring and the trees begin to leaf out.  They fly to the nearest elm tree and begin feeding on the new leaves.
At this time, they lay eggs that hatch in about a week. The larvae feed for two or three weeks, then drop or crawl to the base of the tree, where they pupate. After about 10 days, the adults emerge.  Successive generations can occur through the summer and into the autumn, before Winter returns and they seek places to hibernate.

Our team have successfully treated and controlled the infestation on many private and council trees across the region. Give us a call on 0498 176 484 for approximate costs for treating your trees and your specific requirements.

What is Dutch Elm Disease?

Dutch Elm disease is not the same as having an issue with Elm leaf beetles. 

Dutch Elm Disease is actually caused by fungi – Ophiostoma ulmi & Ophiotoma novo-ulmi.

Australia remains largely free of the Dutch Elm disease pathogen at his time, but if the fungi were to be introduced it could easily be spread by Elm leaf beetles, causing significant issues.

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