The wintertime cold temperatures kill off many insects and pests. One pest, however, can survive the cold winter temperatures: emerald ash borer (EAB.) Emerald ash borer has been a destructive, invasive species in the United States for years, and while EAB is most active during spring and summer, these pests spend the winter preparing to feed on nearby ash trees. EAB survive the winter due to them living within trees and a natural “supercooling” ability.
How does EAB Survive the Winter? Trees
One reason that EAB survive the winter is the protection that ash trees provide. When female emerald ash borer lay their eggs between June and August, the beetles lay eggs between layers of outer bark and cracks and crevices of the trunk and major branches. Once the eggs hatch, the larvae burrow deeper into the tree, feeding on the tree until becoming adults in early spring. The outer bark provides insulation to EAB from the cold weather, so the in-tree temperature is more relevant to EAB’s survival than the temperature outside the tree. Trees that receive much sunlight in the winter can also be warmer despite the cold weather. The other primary reason these beetles can survive cold weather is supercooling.
Supercooling is a process of lowering the temperature of gasses or liquids below the freezing points without becoming solids. Many animals use supercooling by producing antifreeze proteins that bind to ice crystals, preventing water molecules from binding to the ice crystals and preventing the ice from spreading. Insects can also produce these proteins and other sugars or alcohols to prevent themselves from freezing. Supercooling is somewhat common among insects, and that process is the other major reason why EAB survive the winter.
Emerald ash borer’s supercooling has a limit on how low the temperature can get to be useful. Most research has shown that a significant portion of larvae begins to die at around -10°F, and the number increases the lower the temperature goes. The extremely cold weather conditions needed to do so are much more common in northern, colder regions such as the Midwest or Canada. Pennsylvania, Delaware, and Maryland winters are unlikely to be cold enough or may only have short extreme cold snaps instead.
What You Can Do During Winter
If you want to keep your trees safe from the effects of EAB, here are a few things you can do during the winter, while EAB larvae are dormant and have yet to spread to other trees.
- Look for signs of emerald ash borer on your property and among your trees.
- Get your trees inspected by a professional, certified arborist.
- Remove EAB-infested trees and care for surrounding trees to reduce the risk of future infestation.
Between October and May is when EAB activity is lowest, so getting your trees inspected (and removed if necessary) will significantly reduce the chance of nearby trees becoming infested.
Contact Stein Tree for Winter Tree Care Services
While the EAB survive the winter, you can contact Stein Tree Service to inspect your trees and manage destructive pests on your property. Stein’s team of ISA certified arborists has hundreds of years of combined experience and knowledge of pest control and EAB management techniques. Our team has provided residents in Pennsylvania, Delaware, and Maryland with tree care services for decades. We strive to maintain your trees’ health, beauty, and value. For more information on our other services, contact us today.