We live in a small terraced house with a very small gravel garden. In the garden we have a few pot plants and a huge birch tree. I noticed recently that all our plants and pretty much every leaf on the birch that I can see are infested with aphids - literally every leaf is packed. I have crushed most of the aphids on our pot plants but I can't do anything for the tree as most of the leaves are out of reach.
DH has sprayed what he could reach with aphid killer but realistically he can't do much as the tree is significantly taller than our house.
I am very worried about the health of the tree. It must have been there decades and if it dies I should imagine it could have implications for the house (subsidence, possibly). Plus it's a beautiful tree and I love it.
Is it at risk of dyimg? What can I do?