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Identifying and Treating the Emerald Ash Borer in Wisconsin

Posted: August 9, 2018

Written by: Wachtel Tree Science

Categories: Disease Treatment | Emerald Ash Borer | Insect Control

For more than 10 years, the Emerald Ash Borer has been destroying ash trees in Wisconsin. Treating your ash trees for the Emerald Ash Borer will not only save you time and money in the long run but it will most importantly save your ash trees. Being able to identify the Emerald Ash Borer in any stage and knowing when to start treatment are two key benefits that will ultimately lead to keeping your ash trees strong and healthy.

The Emerald Ash Borer’s Stages

Stage 1: The Egg

The EAB’s eggs are extremely small. They’re around a millimeter in size and are reddish-brown in color. Adults tend to lay eggs within furrowing bark and within the crown of ash trees. Areas in which their eggs can be spotted include bark cracks and crevices, the surface of the bark or underneath the outer bark.

Emerald Ash Borer eggs on ash tree bark

Stage 2: The Larva

Within 7 to 10 days of being laid, the EAB’s eggs become larva. In this stage, their appearance is flat with white grubs and 22-32mm in length. Once they’re free from their egg, they burrow within the inner bark and cambial layer, creating S-shaped feeding galleries under the bark. The inner bark tissues and the cambium provide them with the source of food they need to continue to grow. These tissues are also responsible for transporting water and nutrients throughout the tree. The larva undergoes 4 instar stages. Larval development is much faster on trees that have already experienced stress.

Emerald Ash Borer larva burrowing in bark

Stage 3: Pre-Pupa

Taking place within the first 7-9 months, the final instar stage is just before it becomes a pupa. During the last instar, the larva will create a small chamber and curve back onto itself into a position that indicates it has entered the pre-pupa stage. They can be found in the bark of thicker trees and in the outer sapwood of thinner trees. They do not feed once they’ve reached the pre-pupa form.

Emerald Ash Borer pre-pupa within tree bark

Stage 4: Pupa

After 4 instars and 10 months, the larva finally begins to turn into the adult beetle.  The pupa is 10-14mm in length and features become significantly more apparent as time goes on. The last feature to appear is the emerald coloration. Similar to its’ pre-stage, the pupa does not feed.

Emerald Ash Borer pupa burrowed in bark

Stage 5: Adult

If you notice a bright green, small beetle ranging between 0.3 and 0.5 inches, then you’re looking at the adult Emerald Ash Borer. The males and females look almost identical and cannot be determined at first glance. They can typically be seen exiting ash trees during the spring season. Adults feed specifically on ash leaves. While the adult’s feeding habits does little damage to the tree, it does change the appearance significantly. Within a month of being an adult, the Emerald Ash Borer is ready to mate and continue the cycle of laying eggs.

Emerald Ash Borer in adult stage on leaf with wings open

Treating For the Emerald Ash Borer

Identifying any of the Emerald Ash Borer signs mentioned above should immediately prompt you to take action. However, treating your ash trees even without clear signs is recommended – especially in quarantined areas. Though it seems as simple as heading to your local lawn care store and picking up some insecticide, EABs are deeply rooted and can defeat many over-the-counter solutions. Successfully and effectively ridding the EAB of your ash trees requires professional assistance done by a certified arborist.

Contact Wachtel Tree Science Today

Regardless of the time of year, the Emerald Ash Borer can be present on your ash trees. Each stage requires different diagnostics that our arborists are educated in performing. Annual evaluations and treatments guarantee that your ash trees will remain safe and healthy. Ash trees full of life can impact the value of your property drastically. Contact us today to get your ash tree evaluation and treatment done for the year! See our page on the Emerald Ash Borer for additional information.

2018-10-25T13:53:07+00:00 August 9th, 2018|