Emerald Ash Borer

Emerald ash borer is a tiny, invasive insect that causes major damage to ash trees, which results in the death of the tree, if not treated. The adult is metallic green and lays eggs in the tree which hatch into larvae. The larvae damage the tree as they feed on wood underneath the bark, creating tunnels that weaken the tree.

It attacks all species of ash trees and has been spreading across Wisconsin over the past decade, though much of the state is still unaffected. It spreads slowly on it’s own, but is spread quickly and easily by humans through transport of infected firewood. That’s why it’s so important to use local firewood to slow the spread of this destructive invasive insect.

Trees can be treated with a systemic insecticide applied into the soil or injected into the tree trunk. It’s best to treat trees preventatively, but they can be treated if infested and damage isn’t too severe, usually less than 50% canopy thinning. We recommend using Bonide Annual Tree & Shrub Insect Control with Systemaxx once a year sometime mid-April to mid-May, according to instructions.

Look for signs and symptoms of an emerald ash borer infestation. For already infested trees, consult an arborist about treatment options, including the possible effectiveness of treatment and cost. If a tree is infested and too far gone, the only option may be to remove it.