Does Winter Save Your Trees From Emerald Ash Borer?

Ontario winters are cold, snowy, and long, but people get a nice reprieve from the buzzing, biting, swarming of insects. You would think that your trees would, too. If you have ash trees, you may look forward to the cold months, assuming the iridescent green pests that were intent on feasting their way through the ash on your property would die off. You may think that if the grand, deciduous beauties survived this season, you are saved from cutting down trees as they fall to these beastly bugs. Unfortunately, you can count the emerald ash borer among the hardy that can survive an Ontario winter.

Stages of EAB Life

EABs only live for a year or two, but, like most insects, they are prolific breeders. Their populations can grow rapidly, killing an infested tree in two to four years. The bugs are destructive at almost every stage of their lives. In the spring, when the adults emerge from the tree — after chewing through the bark — they feast on the leaves at the canopy, eventually leaving branches bare.

The mating season occurs in the summer, during which the females may lay up to 150 eggs under the bark and in the cracks and crevices of your ash trees. The eggs hatch hungry larvae two weeks later. They tunnel through the outer layers of the tree, cutting off the flow of water and nutrients. As winter hits, they’ll be tucked up tight in their pupation cells, while waiting out the cold. In early spring, the larvae pupate and develop into adults ready to feast on leaves as they bore a hole through the ash tree bark.

Survival in the Dead of Winter

The emerald ash borer larvae are surprisingly adept at making it through an Ontario winter. They go dormant when the cold hits, hibernating within the confines of their pupate cells. These cells provide insulation from the temperatures outside. The outer layers of the tree shelter them from the elements, giving them another layer of protection. Those larvae that happen to be on the sunny side of their winter home get the benefits of the sun’s warmth.

These factors contribute significantly to emerald ash borer survival. When you add in the fact that the larvae have a low freezing level, you can see why winter doesn’t necessarily mean your EAB troubles are over. The larvae can survive temperatures as low as -23 to -31 degrees Celsius. While the cold might kill the weaker individuals, those that make it reproduce and pass on their survival traits to their offspring, increasing the chances that more EABs get through the cold months the next time around.

Signs of Trouble for Your Trees

If you have ash trees on your property, you should know how to spot the signs of EAB trouble early and take care of the problem before it gets out of control. The adult emerald ash borer eats leaves from the crown, working its way down from the top. This can make it rather difficult to see early signs of damage 30 meters up.

Often, the primary indicator of an EAB problem is the appearance of more woodpeckers on your ash trees than normal. The birds love the larvae, so if you see them pecking away at your ash trees, you may have an infestation. Another sign to look for is the serpentine galleries the larvae leave behind as they feed in the tree’s sapwood layer. You can see these if you peel away some of the bark.

Help for Your Ash Trees

Martin’s Tree Service has the expertise to diagnose an emerald ash borer problem and help you deal with it. Cutting down infected and unhealthy trees is a dangerous job best left to professionals. If you suspect you have an EAB problem, or you want to reduce the likelihood of one, get in touch with us for a free consultation to find out what we can do for you.