Its not the aphid you need to worry about killing the willows its the councilsGood to hear the comment about the willow aphid. How do you find extracting the cement honey? Also, what about the damage to the willows? Spoiling of sheep wool? Sorry - another thread.
They are spraying anything that looks like a willow under some daft idea they need to be replaced with native trees. If you keep an eye out on your travels you will see large areas of dead willows councils have sprayed out The lakes by Ohaupo are good example
Dont have concrete its just rather grainy