The Elm Leaf Beetle problem....

Here at Rahamim, there is a problem with Elm Leaf Beetle. This beetle has come to this area in the last few years. Common treatments include poisoning with an insecticide (imdacloprid). What does this insecticide do to the environment? How does this insecticide target just the Elm Leaf Beetle? Does it have an effect on other insects that are beneficial to our environment? How do bees respond to this insecticide? What does this insecticide do to the soil that supports the tree?

The best way to deal with any problem insect is to find the weakest point in its life-cycle and find the best way to control it at that point. The life cycle of the elm leaf beetle starting at the adult stage, an adult bug it eats the young leaves from the tree in Spring. The females then lay eggs on the underside of the leaf. Eggs hatch in 7 – 10 days. The larvae increase in size to about 12mm, then they migrate down the tree trunk around December/January. They then find a nice spot in the crevices of the trunk, or in the soil and pupate and 1 – 2 weeks later emerge as a beetle. 

The weakest point of the lifecycle of the beetle would be when they are eggs on the underside of the leaf, or when they are in the pupating stage. At both points these bugs are stationary. Let us assume that we cannot find the eggs – as they are scattered through the leaves. Leave those for the birds to control. We can access the beetle when they are coming down the trunk of the tree to pupate.

The most common and natural way to deal with the beetle at this stage is to wrap sticky tape around the base of the tree (sticky side out), about 20cm wide for the bugs to get caught in. This is what we are doing here at Rahamim. There are even more measures we could take - add some animals to do the work. Ideally we would also add either chickens, ducks or guinea fowl to devour the bugs as they descend down the tree. We are looking into measures of how to keep the chickens safe (from Mr Fox!) and contained around the tree as they do their work to help us control the beetle and to maintain these beautiful trees.

Do you know of any other measure we could take? What has your experience been with the control of this beetle?