The hemlock woolly adelgid is a strange insect. Unlike most insects that are dormant during the winter and become active when it’s warm, adelgids prefer cool weather, and actually go dormant during the summer. Their most active times are in the early spring, and late into the fall.
They do this to coincide their activity with that of their only host, the hemlock tree. Hemlocks, being evergreens, are able to function whenever the weather is not extremely cold, but they have cycles in their production of defensive chemicals, and in water use. While we treat hemlocks much of the year when soil moisture is adequate, late winter into early spring is the optimal time, because water is available and the trees are active, and the chemical can get into the tree to coincide with the rise in feeding as weather warms slightly.
Remember: if you have hemlock trees, they must be managed now for adelgid. They have no immunity at all to this non-native insect. Please call Snow Creek to help you with your hemlocks, and with all of your tree care needs.