Not a lot,if it's a big tree. Maybe the birds are helping........to feed young. If you do spray something on it make sure you follow all precautions on the packaging. Not on a windy day. Ask at your garden centre what might be best to use, and the safest, or let the tree cope if it is large. We never sprayed our huge cherries when infested they were just too big.

Neem oil is a safe, if slow acting, spray, but spraying a big tree requires big agricultural equipment--often better to let nature take its course, and breed up a big crop of beneficial insects.

thanks. It's not a big tree, it's a fan on a wall.

I'd go ahead and spray it with neem, then, Christabel. You could add a little dishwashing soap to keep the aphids down while the neem works.

thankyou